#include <stdio.h>
#include <limits.h>
 
#define INF INT_MAX
int N;
int Dist[500];
int Q[500];
int Visited[500];
int Graph[500][500];
 
void Dijkstra(int b){
     int H = 0;
     int T = -1;
     int j,k;
 
Dist[b] = 0;
 
Q[T+1] = b;
T = T+1;
 
while(T>=H){
    j = Q[H];
    Visited[j] = 1;
    for (k = 0;k < N; k++){
        if(!Visited[k] && Dist[k] > Graph[j][k] + Dist[j] && Graph[j][k] != -1){
            Dist[k] = Dist[j]+Graph[j][k];
            Q[T+1] = k;
            T = T+1;
        }
    }
 
    H = H+1;
}
}  
 
int main(){
 
int src,target,m;
int a,w,b,i,j;
 
scanf("%d%d%d%d",&N,&m,&src,&target);
 
for(i = 0;i < N;i ++){
    for(j = 0;j < N;j++){
        Graph[i][j] = -1;
    }
}
 
for(i = 0; i< N; i++){
    Dist[i] = INF;
    Visited[i] = 0;
}
 
 
for(i = 0;i < m; i++){
    scanf("%d%d%d",&a,&b,&w);
    a--;
    b--;
    Graph[a][b] = w;
    Graph[b][a] = w;
}
 
Dijkstra(src-1);
 
 
if(Dist[target-1] == INF){
    printf("NO");
}else {
    printf("YES\n%d",Dist[target-1]);
}
 
return 0;
}

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5 3 2
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