int adjv;

int weight;

AdjNode(int adjv, int weight) : adjv(adjv), weight(weight) {}

int v;

int dist;

PNode(int v, int dist) : v(v), dist(dist) {}

bool operator()(PNode& a, PNode& b) {

return a.dist > b.dist;

}

memset(dist, 0xff, sizeof(dist)); //-1

memset(collected, 0, sizeof(collected)); //false

dist[s] = 0;

q.push(PNode(s, 0));

while (!q.empty()) {

int v = q.top().v;

q.pop();

if (collected[v]) continue;

collected[v] = true;

if (v == t) break;

for (auto it = graph[v].begin(); it != graph[v].end(); it++) {

int w = it->adjv;

if (dist[w] == -1 || dist[v] + it->weight < dist[w]) {

dist[w] = dist[v] + it->weight;

q.push(PNode(w, dist[w]));

}

}

}

return dist[t];

int n, m, s, t, u, v, w;

scanf("%d %d %d %d", &n, &m, &s, &t);

s--; t--;

for (int i = 0; i < m; i++) {

scanf("%d %d %d", &u, &v, &w);

u--; v--;

graph[v].push_back(AdjNode(u, w));

graph[u].push_back(AdjNode(v, w));

}

printf("%d", dijkstra(s, t));

exit(0);