/**

final int signum;

/**

final int[] mag;

// The following fields are stable variables. A stable variable's value

// changes at most once from the default zero value to a non-zero stable

// value. A stable value is calculated lazily on demand.

/**

private int bitCountPlusOne;

/**

private int magBitLengthPlusOne;

/**

private int lowestSetBitPlusTwo;

/**

private int numberOfTrailingZeroIntsPlusTwo;

/**

static final long LONG_MASK = 0xffffffffL;

/**

private static final int MAX_MAG_LENGTH = Integer.MAX_VALUE / Integer.SIZE + 1; // (1 << 26)

/**

private static final int PRIME_SEARCH_BIT_LENGTH_LIMIT = 500000000;

/**

private static final int KARATSUBA_THRESHOLD = 80;

/**

private static final int TOOM_COOK_THRESHOLD = 240;

/**

private static final int KARATSUBA_SQUARE_THRESHOLD = 128;

/**

private static final int TOOM_COOK_SQUARE_THRESHOLD = 216;

/**

static final int BURNIKEL_ZIEGLER_THRESHOLD = 80;

/**

static final int BURNIKEL_ZIEGLER_OFFSET = 40;

/**

private static final int SCHOENHAGE_BASE_CONVERSION_THRESHOLD = 20;

/**

private static final int MULTIPLY_SQUARE_THRESHOLD = 20;

/**

private static final int MONTGOMERY_INTRINSIC_THRESHOLD = 512;

// Constructors

/**

public BigInteger(byte[] val, int off, int len) {

if (val.length == 0) {

throw new NumberFormatException("Zero length BigInteger");

}

Objects.checkFromIndexSize(off, len, val.length);

if (len == 0) {

mag = ZERO.mag;

signum = ZERO.signum;

return;

}

int b = val[off];

if (b < 0) {

mag = makePositive(b, val, off, len);

signum = -1;

} else {

mag = stripLeadingZeroBytes(b, val, off, len);

signum = (mag.length == 0 ? 0 : 1);

}

if (mag.length >= MAX_MAG_LENGTH) {

checkRange();

}

}

/**

public BigInteger(byte[] val) {

this(val, 0, val.length);

}

/**

private BigInteger(int[] val) {

if (val.length == 0)

throw new NumberFormatException("Zero length BigInteger");

if (val[0] < 0) {

mag = makePositive(val);

signum = -1;

} else {

mag = trustedStripLeadingZeroInts(val);

signum = (mag.length == 0 ? 0 : 1);

}

if (mag.length >= MAX_MAG_LENGTH) {

checkRange();

}

}

/**

public BigInteger(int signum, byte[] magnitude, int off, int len) {

if (signum < -1 || signum > 1) {

throw(new NumberFormatException("Invalid signum value"));

}

Objects.checkFromIndexSize(off, len, magnitude.length);

// stripLeadingZeroBytes() returns a zero length array if len == 0

this.mag = stripLeadingZeroBytes(magnitude, off, len);

if (this.mag.length == 0) {

this.signum = 0;

} else {

if (signum == 0)

throw(new NumberFormatException("signum-magnitude mismatch"));

this.signum = signum;

}

if (mag.length >= MAX_MAG_LENGTH) {

checkRange();

}

}

/**

public BigInteger(int signum, byte[] magnitude) {

this(signum, magnitude, 0, magnitude.length);

}

/**

private BigInteger(int signum, int[] magnitude) {

this.mag = stripLeadingZeroInts(magnitude, false);

if (signum < -1 || signum > 1)

throw(new NumberFormatException("Invalid signum value"));

if (this.mag.length == 0) {

this.signum = 0;

} else {

if (signum == 0)

throw(new NumberFormatException("signum-magnitude mismatch"));

this.signum = signum;

}

if (mag.length >= MAX_MAG_LENGTH) {

checkRange();

}

}

/**

public BigInteger(String val, int radix) {

int cursor = 0, numDigits;

final int len = val.length();

if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)

throw new NumberFormatException("Radix out of range");

if (len == 0)

throw new NumberFormatException("Zero length BigInteger");

// Check for at most one leading sign

int sign = 1;

int index1 = val.lastIndexOf('-');

int index2 = val.lastIndexOf('+');

if (index1 >= 0) {

if (index1 != 0 || index2 >= 0) {

throw new NumberFormatException("Illegal embedded sign character");

}

sign = -1;

cursor = 1;

} else if (index2 >= 0) {

if (index2 != 0) {

throw new NumberFormatException("Illegal embedded sign character");

}

cursor = 1;

}

if (cursor == len)

throw new NumberFormatException("Zero length BigInteger");

// Skip leading zeros and compute number of digits in magnitude

while (cursor < len &&

Character.digit(val.charAt(cursor), radix) == 0) {

cursor++;

}

if (cursor == len) {

signum = 0;

mag = ZERO.mag;

return;

}

numDigits = len - cursor;

signum = sign;

// Pre-allocate array of expected size. May be too large but can

// never be too small. Typically exact.

long numBits = ((numDigits * bitsPerDigit[radix]) >>> 10) + 1;

if (numBits + 31 >= (1L << 32)) {

reportOverflow();

}

int numWords = (int) (numBits + 31) >>> 5;

int[] magnitude = new int[numWords];

// Process first (potentially short) digit group

int firstGroupLen = numDigits % digitsPerInt[radix];

if (firstGroupLen == 0)

firstGroupLen = digitsPerInt[radix];

String group = val.substring(cursor, cursor += firstGroupLen);

magnitude[numWords - 1] = Integer.parseInt(group, radix);

if (magnitude[numWords - 1] < 0)

throw new NumberFormatException("Illegal digit");

// Process remaining digit groups

int superRadix = intRadix[radix];

int groupVal = 0;

while (cursor < len) {

group = val.substring(cursor, cursor += digitsPerInt[radix]);

groupVal = Integer.parseInt(group, radix);

if (groupVal < 0)

throw new NumberFormatException("Illegal digit");

destructiveMulAdd(magnitude, superRadix, groupVal);

}

// Required for cases where the array was overallocated.

mag = trustedStripLeadingZeroInts(magnitude);

if (mag.length >= MAX_MAG_LENGTH) {

checkRange();

}

}

/*

BigInteger(char[] val, int sign, int len) {

int cursor = 0, numDigits;

// Skip leading zeros and compute number of digits in magnitude

while (cursor < len && Character.digit(val[cursor], 10) == 0) {

cursor++;

}

if (cursor == len) {

signum = 0;

mag = ZERO.mag;

return;

}

numDigits = len - cursor;

signum = sign;

// Pre-allocate array of expected size

int numWords;

if (len < 10) {

numWords = 1;

} else {

long numBits = ((numDigits * bitsPerDigit[10]) >>> 10) + 1;

if (numBits + 31 >= (1L << 32)) {

reportOverflow();

}

numWords = (int) (numBits + 31) >>> 5;

}

int[] magnitude = new int[numWords];

// Process first (potentially short) digit group

int firstGroupLen = numDigits % digitsPerInt[10];

if (firstGroupLen == 0)

firstGroupLen = digitsPerInt[10];

magnitude[numWords - 1] = parseInt(val, cursor, cursor += firstGroupLen);

// Process remaining digit groups

while (cursor < len) {

int groupVal = parseInt(val, cursor, cursor += digitsPerInt[10]);

destructiveMulAdd(magnitude, intRadix[10], groupVal);

}

mag = trustedStripLeadingZeroInts(magnitude);

if (mag.length >= MAX_MAG_LENGTH) {

checkRange();

}

}

// Create an integer with the digits between the two indexes

// Assumes start < end. The result may be negative, but it

// is to be treated as an unsigned value.

private int parseInt(char[] source, int start, int end) {

int result = Character.digit(source[start++], 10);

if (result == -1)

throw new NumberFormatException(new String(source));

for (int index = start; index < end; index++) {

int nextVal = Character.digit(source[index], 10);

if (nextVal == -1)

throw new NumberFormatException(new String(source));

result = 10*result + nextVal;

}

return result;

}

// bitsPerDigit in the given radix times 1024

// Rounded up to avoid underallocation.

private static long bitsPerDigit[] = { 0, 0,

1024, 1624, 2048, 2378, 2648, 2875, 3072, 3247, 3402, 3543, 3672,

3790, 3899, 4001, 4096, 4186, 4271, 4350, 4426, 4498, 4567, 4633,

4696, 4756, 4814, 4870, 4923, 4975, 5025, 5074, 5120, 5166, 5210,

5253, 5295};

// Multiply x array times word y in place, and add word z

private static void destructiveMulAdd(int[] x, int y, int z) {

// Perform the multiplication word by word

long ylong = y & LONG_MASK;

long zlong = z & LONG_MASK;

int len = x.length;

long product = 0;

long carry = 0;

for (int i = len-1; i >= 0; i--) {

product = ylong * (x[i] & LONG_MASK) + carry;

x[i] = (int)product;

carry = product >>> 32;

}

// Perform the addition

long sum = (x[len-1] & LONG_MASK) + zlong;

x[len-1] = (int)sum;

carry = sum >>> 32;

for (int i = len-2; i >= 0; i--) {

sum = (x[i] & LONG_MASK) + carry;

x[i] = (int)sum;

carry = sum >>> 32;

}

}

/**

public BigInteger(String val) {

this(val, 10);

}

/**

public BigInteger(int numBits, Random rnd) {

byte[] magnitude = randomBits(numBits, rnd);

try {

// stripLeadingZeroBytes() returns a zero length array if len == 0

this.mag = stripLeadingZeroBytes(magnitude, 0, magnitude.length);

if (this.mag.length == 0) {

this.signum = 0;

} else {

this.signum = 1;

}

if (mag.length >= MAX_MAG_LENGTH) {

checkRange();

}

} finally {

Arrays.fill(magnitude, (byte)0);

}

}

private static byte[] randomBits(int numBits, Random rnd) {

if (numBits < 0)

throw new IllegalArgumentException("numBits must be non-negative");

int numBytes = (int)(((long)numBits+7)/8); // avoid overflow

byte[] randomBits = new byte[numBytes];

// Generate random bytes and mask out any excess bits

if (numBytes > 0) {

rnd.nextBytes(randomBits);

int excessBits = 8*numBytes - numBits;

randomBits[0] &= (byte)((1 << (8-excessBits)) - 1);

}

return randomBits;

}

/**

public BigInteger(int bitLength, int certainty, Random rnd) {

BigInteger prime;

if (bitLength < 2)

throw new ArithmeticException("bitLength < 2");

prime = (bitLength < SMALL_PRIME_THRESHOLD

? smallPrime(bitLength, certainty, rnd)

: largePrime(bitLength, certainty, rnd));

signum = 1;

mag = prime.mag;

}

// Minimum size in bits that the requested prime number has

// before we use the large prime number generating algorithms.

// The cutoff of 95 was chosen empirically for best performance.

private static final int SMALL_PRIME_THRESHOLD = 95;

// Certainty required to meet the spec of probablePrime

private static final int DEFAULT_PRIME_CERTAINTY = 100;

/**

public static BigInteger probablePrime(int bitLength, Random rnd) {

if (bitLength < 2)

throw new ArithmeticException("bitLength < 2");

return (bitLength < SMALL_PRIME_THRESHOLD ?

smallPrime(bitLength, DEFAULT_PRIME_CERTAINTY, rnd) :

largePrime(bitLength, DEFAULT_PRIME_CERTAINTY, rnd));

}

/**

private static BigInteger smallPrime(int bitLength, int certainty, Random rnd) {

int magLen = (bitLength + 31) >>> 5;

int temp[] = new int[magLen];

int highBit = 1 << (bitLength - 1); // High bit of high int

int highMask = (highBit << 1) - 1; // Bits to keep in high int

while (true) {

// Construct a candidate

for (int i=0; i < magLen; i++)

temp[i] = rnd.nextInt();

temp[0] = (temp[0] & highMask) | highBit; // Ensure exact length

if (bitLength > 2)

temp[magLen-1] |= 1; // Make odd if bitlen > 2

BigInteger p = new BigInteger(temp, 1);

// Do cheap "pre-test" if applicable

if (bitLength > 6) {

long r = p.remainder(SMALL_PRIME_PRODUCT).longValue();

if ((r%3==0) || (r%5==0) || (r%7==0) || (r%11==0) ||

(r%13==0) || (r%17==0) || (r%19==0) || (r%23==0) ||

(r%29==0) || (r%31==0) || (r%37==0) || (r%41==0))

continue; // Candidate is composite; try another

}

// All candidates of bitLength 2 and 3 are prime by this point

if (bitLength < 4)

return p;

// Do expensive test if we survive pre-test (or it's inapplicable)

if (p.primeToCertainty(certainty, rnd))

return p;

}

}

private static final BigInteger SMALL_PRIME_PRODUCT

= valueOf(3L*5*7*11*13*17*19*23*29*31*37*41);

/**

private static BigInteger largePrime(int bitLength, int certainty, Random rnd) {

BigInteger p;

p = new BigInteger(bitLength, rnd).setBit(bitLength-1);

p.mag[p.mag.length-1] &= ~1;

// Use a sieve length likely to contain the next prime number

int searchLen = getPrimeSearchLen(bitLength);

BitSieve searchSieve = new BitSieve(p, searchLen);

BigInteger candidate = searchSieve.retrieve(p, certainty, rnd);

while ((candidate == null) || (candidate.bitLength() != bitLength)) {

p = p.add(BigInteger.valueOf(2*searchLen));

if (p.bitLength() != bitLength)

p = new BigInteger(bitLength, rnd).setBit(bitLength-1);

p.mag[p.mag.length-1] &= ~1;

searchSieve = new BitSieve(p, searchLen);

candidate = searchSieve.retrieve(p, certainty, rnd);

}

return candidate;

}

/**

public BigInteger nextProbablePrime() {

if (this.signum < 0)

throw new ArithmeticException("start < 0: " + this);

// Handle trivial cases

if ((this.signum == 0) || this.equals(ONE))

return TWO;

BigInteger result = this.add(ONE);

// Fastpath for small numbers

if (result.bitLength() < SMALL_PRIME_THRESHOLD) {

// Ensure an odd number

if (!result.testBit(0))

result = result.add(ONE);

while (true) {

// Do cheap "pre-test" if applicable

if (result.bitLength() > 6) {

long r = result.remainder(SMALL_PRIME_PRODUCT).longValue();

if ((r%3==0) || (r%5==0) || (r%7==0) || (r%11==0) ||

(r%13==0) || (r%17==0) || (r%19==0) || (r%23==0) ||

(r%29==0) || (r%31==0) || (r%37==0) || (r%41==0)) {

result = result.add(TWO);

continue; // Candidate is composite; try another

}

}

// All candidates of bitLength 2 and 3 are prime by this point

if (result.bitLength() < 4)

return result;

// The expensive test

if (result.primeToCertainty(DEFAULT_PRIME_CERTAINTY, null))

return result;

result = result.add(TWO);

}

}

// Start at previous even number

if (result.testBit(0))

result = result.subtract(ONE);

// Looking for the next large prime

int searchLen = getPrimeSearchLen(result.bitLength());

while (true) {

BitSieve searchSieve = new BitSieve(result, searchLen);

BigInteger candidate = searchSieve.retrieve(result,

DEFAULT_PRIME_CERTAINTY, null);

if (candidate != null)

return candidate;

result = result.add(BigInteger.valueOf(2 * searchLen));

}

}

private static int getPrimeSearchLen(int bitLength) {

if (bitLength > PRIME_SEARCH_BIT_LENGTH_LIMIT + 1) {

throw new ArithmeticException("Prime search implementation restriction on bitLength");

}

return bitLength / 20 * 64;

}

/**

boolean primeToCertainty(int certainty, Random random) {