#include <iostream>#include <queue>#include <cstring>#include <vector>#include <algorithm>#include <cstdio>#define Heap pair<int,int>using namespace std;priority_queue< Heap,vector<Heap>,greater<Heap> > s;const int MAXN=20005;struct node{    int u,v,w,next;    node() {}    node(int _u,int _v,int _w,int _next){        u = _u,v = _v, w = _w,next = _next;    }}G[MAXN];int n,m,start,end,Count,head[MAXN],dis[MAXN];void AddEdge(int u,int v,int w){    G[Count] = node(u,v,w,head[u]);    head[u] = Count++;}void Dij(int x){    for(int i=1;i<=n;i++) dis[i]=999999999;    dis[x] = 0;    s.push(make_pair(dis[x],x));    while( !s.empty() ){        Heap N = s.top();        s.pop();        int fuck = N.second;        if(dis[fuck]!=N.first) continue;        for(int e = head[fuck];e != -1;e=G[e].next){            int v =G[e].v;            int w =G[e].w;            if(dis[fuck]+w<dis[v]){                dis[v] = dis [fuck] + w;                s.push(make_pair(dis[v],v));            }        }    }    printf("%d\n",dis[end]);    return;}int main(){    memset(head,-1,sizeof(head));    scanf("%d%d%d%d",&n,&m,&start,&end);    for(int i=1;i<=m;i++){        int x,y,z;        scanf("%d%d%d",&x,&y,&z);        AddEdge(x,y,z);        AddEdge(y,x,z);    }        Dij(start);    return 0;}