__author__ = 'Avinash'

a = float(input('Enter first side: '))
b = float(input('Enter second side: '))
c = float(input('Enter third side: '))

s = (a + b + c) / 2

area = (s * (s - a) * (s - b) * (s - c)) ** 0.5
print('The area of the triangle is %0.2f' % area)