#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
#define N 205
#define M 1005
#define INF 999999999
int city[N][N];
int dist[M];
int n;

void Dijkstra(int v0)
{
    int S[N];
    for(int i=0; i<n; i++)
    {
        dist[i]=city[v0][i];
        S[i]=0;
    }
    dist[v0]=0;
    S[v0]=1;
    for(int i=1; i<n; i++)
    {
        int mindist=INF;
        int flag=v0;
        for(int j=0; j<n; j++)
            if((!S[j])&&dist[j]<mindist)
            {
                flag=j;
                mindist=dist[j];
            }
        S[flag]=1;
        for(int j=0; j<n; j++)
            if((!S[j])&&city[flag][j]<INF)
            {
                if(dist[j]>dist[flag]+city[flag][j])
                    dist[j]=dist[flag]+city[flag][j];
            }
    }
}

int main()
{
    int m,a,b,x;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        for(int i=0; i<n; i++)
            for(int j=0; j<n; j++)
            {
                if(i==j)
                    city[i][j]=0;
                else
                    city[i][j]=INF;
            }

        for(int i=0; i<m; i++)
        {
            scanf("%d%d%d",&a,&b,&x);
            if(x<city[a][b])
            {
                city[a][b]=x;
                city[b][a]=x;
            }
        }
        scanf("%d%d",&a,&b);

        Dijkstra(a);
        if(dist[b]==INF)
            printf("-1\n");
        else
            printf("%d\n",dist[b]);
    }
    return 0;
}

#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;

#define N 205
#define M 1005
#define INF 999999999
int city[N][N];
int n;

void floyd()
{
    for(int k=0; k<n; k++)
        for(int i=0; i<n; i++)
            for(int j=0; j<n; j++)
            {
                if(city[i][j]>city[i][k]+city[k][j])
                    city[i][j]=city[i][k]+city[k][j];
            }
}
int main()
{
    int m,a,b,x;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        for(int i=0; i<n; i++)
            for(int j=0; j<n; j++)
            {
                if(i==j)
                    city[i][j]=0;
                else
                    city[i][j]=INF;
            }

        for(int i=0; i<m; i++)
        {
            scanf("%d%d%d",&a,&b,&x);
            if(x<city[a][b])
            {
                city[a][b]=x;
                city[b][a]=x;
            }
        }
        scanf("%d%d",&a,&b);
        floyd();
        if(city[a][b]==INF)
            printf("-1\n");
        else
            printf("%d\n",city[a][b]);
    }
    return 0;
}