1 #include <iostream>
 2 #include <cstdio>
 3 #include <algorithm>
 4 #include <cstring>
 5 #include <queue>
 6 using namespace std;
 7 const int maxn = 205;
 8 const int INF = 0x3f3f3f3f;
 9 struct edge{
10     int to,cost;
11     friend bool operator < (edge A,edge B){
12         return A.cost > B.cost;
13     }
14 };
15 int d[maxn];
16 vector<edge> g[maxn];
17 bool done[maxn];
18 void dijkstra(int s){
19     memset(d,INF,sizeof(d));
20     memset(done,false,sizeof(done));
21     d[s] = 0;
22     priority_queue<edge> q;
23     q.push((edge){s,0});
24     while(!q.empty()){
25         edge cur = q.top(); q.pop();
26         int v = cur.to;
27         if(done[v]) continue;
28         done[v] = true;
29         for(int i = 0; i<g[v].size(); i++){
30             edge e = g[v][i];
31             if(d[e.to]>d[v]+e.cost){
32                 d[e.to] = d[v]+e.cost;
33                 q.push((edge){e.to,d[e.to]});
34             }
35         }
36     }
37 }
38 void solve(){
39     int n,m;
40     while(scanf("%d%d",&n,&m)!=EOF){
41         for(int i = 0; i<m; i++){
42             int a,b,c;
43             scanf("%d%d%d",&a,&b,&c);
44             g[a].push_back((edge){b,c});
45             g[b].push_back((edge){a,c});
46         }
47         int s,t;
48         scanf("%d%d",&s,&t);
49         dijkstra(s);
50         if(d[t] == INF) printf("-1\n");
51         else printf("%d\n",d[t]);
52         for(int i = 0; i<maxn; i++) g[i].clear();
53     }
54 }
55 int main()
56 {
57     solve();
58     return 0;
59 }