/************************************************************************/
/*     hdu  畅通工程续dijkstra求起始点到目标点最短距离题目大意：求这些村子中从起始位置到目标点的最短距离解题思路：dijkstra算法，求图中两个点的最短距离,　　　　　　dijkstra算法不同于prim算法，prim算法是求虽小生成树，　　　　　　不断地把点最近的点加入到集合中；而dijkstra算法是求源点到目标点的最短距离。
*/
/************************************************************************/#include <stdio.h>
#include <string.h>
#include <algorithm>#define MAX 0xfffffff
const int N = 201;int dj[N],map[N][N],vis[N];
int n,m,x,y,len,i,j;void DJ(int start,int end)
{int min,k;int t = n;int cur = start;for(i=0;i<n;dj[i++]=MAX); dj[start] = 0;while(1){min = MAX;vis[cur] = 1;for(i = 0; i < n; i++){if(vis[i]==1)continue;if(dj[i] > map[i][cur] + dj[cur])//dj[i] = map[i][cur] + dj[cur];if(min>dj[i]){min = dj[i];k = i;}}cur = k;if(cur == end)break;if(min == MAX)break;}printf("%d\n",dj[end]<MAX?dj[end]:-1);
}int main()
{while(scanf("%d%d",&n,&m)!= EOF){memset(vis,0,sizeof(vis));for (i = 0; i < n; i++)for (j = 0; j < n; j++){map[i][j] = (i==j?0:MAX);}for (i = 1; i <= m; i++){scanf("%d%d%d",&x,&y,&len);map[x][y] = map[y][x] = (map[x][y]<len?map[x][y]:len);}scanf("%d%d",&x,&y);DJ(x,y);}return 0;
}

/************************************************************************/
/*     hdu  畅通工程续floyd 求起始点到目标点最短距离题目大意：求这些村子中从起始位置到目标点的最短距离解题思路：floyd 算法，求图中两个点的最短距离floyd算法就是在整个图中扫描，看点 i 到 j 的距离和（点 i 到点 k 的距离）+（点 k 到点 j 的距离）两者哪个较小，把小的存入map[i][j]中即可。
*/
/************************************************************************/#include <stdio.h>
#include <string.h>
#include <algorithm>#define MIN(a,b) a<b?a:b
#define MAX 0xfffffff
const int N = 201;int map[N][N];
int n,m,x,y,len,i,j;void floyd(int start,int end)
{int k;for (k = 0; k < n; k++){for (i = 0; i < n; i++)for (j = 0; j < n; j++)map[i][j] = MIN(map[i][j],map[i][k]+map[k][j]);}printf("%d\n",map[start][end]<MAX?map[start][end]:-1);
}int main()
{while(scanf("%d%d",&n,&m)!= EOF){for (i = 0; i < n; i++)for (j = 0; j < n; j++){map[i][j] = (i==j?0:MAX);}for (i = 1; i <= m; i++){scanf("%d%d%d",&x,&y,&len);map[x][y] = map[y][x] = (map[x][y]<len?map[x][y]:len);}scanf("%d%d",&x,&y);floyd(x,y);}return 0;
}