[cce_cpp]
#include <iostream>
#include <algorithm>
using namespace std;
#ifndef ONLINE_JUDGE
//最开始想用来练习spfa+邻接表，老是wa,改用floyd + 邻接矩阵，还是wa，最后无奈看了discuss,
//才发现忘记判断起点与终点相同的情况...
#include <fstream>
ifstream fin("test.txt");
#define cin fin
#endif
const int INF = 99999999;
int graph[220][220];
int main()
{
ios::sync_with_stdio(false);
int n,m,i,a,b,x,s,t,k,j;
while(cin >> n >> m)
{
for(i = 0; i < n; ++i)
{
for(j = 0; j < n; ++j)
if(i==j)
graph[i][j]=0;
else
graph[i][j] = INF;
}
for(i = 0; i < m; ++i)
{
cin >> a >> b >> x;
graph[a][b] = graph[b][a] = x < graph[a][b] ? x : graph[a][b];
}
cin >> s >> t;
for(k = 0; k < n; ++k)
for(i = 0; i < n; ++i)
for(j = 0; j < n; ++j)
if(graph[i][j] > graph[i][k] + graph[k][j])
graph[i][j] = graph[i][k] + graph[k][j];
if(graph[s][t]==INF)
cout << -1 << endl;
else
cout << graph[s][t] << endl;
}
return 0;
}
[/cce_cpp]
