#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <queue>
#include <vector>
#include <iomanip>
#include <math.h>
#include <map>
using namespace std;
#define FIN     freopen("input.txt","r",stdin);
#define FOUT    freopen("output.txt","w",stdout);
#define INF     0x3f3f3f3f
#define lson    l,m,rt<<1
#define rson    m+1,r,rt<<1|1
typedef long long LL;int Map[205][205];
int n,m;int llss(int s,int e){for(int z=0;z<n;z++)for(int i=0;i<n;i++)for(int j=0;j<n;j++){if(Map[i][j]>Map[i][z]+Map[z][j])Map[i][j]=Map[i][z]+Map[z][j];}if(Map[s][e]==INF)return -1;elsereturn Map[s][e];}int main()
{//FINint st,ed,cost;int s,e;while(~scanf("%d%d",&n,&m)){memset(Map,INF,sizeof(Map));for(int i=0;i<n;i++){Map[i][i]=0;}for(int i=1;i<=m;i++){scanf("%d%d%d",&st,&ed,&cost);Map[ed][st]=Map[st][ed]=min(Map[st][ed],cost);}scanf("%d%d",&s,&e);int ans=llss(s,e);printf("%d\n",ans);}
}

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <queue>
#include <vector>
#include <iomanip>
#include <math.h>
#include <map>
using namespace std;
#define FIN     freopen("input.txt","r",stdin);
#define FOUT    freopen("output.txt","w",stdout);
#define INF     0x3f3f3f3f
#define lson    l,m,rt<<1
#define rson    m+1,r,rt<<1|1
typedef long long LL;const int MAXN=205;int Map[MAXN][MAXN];
int dis[MAXN];
int vis[MAXN];
int n,m;int llss(int s,int e){for(int i=0;i<n;i++){dis[i]=Map[s][i];vis[i]=0;}vis[s]=1;dis[s]=0;int temp,k;for(int i=0;i<n;i++){temp=INF;for(int j=0;j<n;j++){if(vis[j]==0&&temp>dis[j]){k=j;temp=dis[j];}}if(temp==INF)  break;vis[k]=1;for(int j=0;j<n;j++){if(dis[j]>dis[k]+Map[k][j])  dis[j]=dis[k]+Map[k][j];}}if(dis[e]==INF)  return -1;else return dis[e];}int main()
{//FINint st,ed,cost;int s,e;while(~scanf("%d%d",&n,&m)){memset(Map,INF,sizeof(Map));for(int i=0;i<n;i++){Map[i][i]=0;}for(int i=1;i<=m;i++){scanf("%d%d%d",&st,&ed,&cost);Map[ed][st]=Map[st][ed]=min(Map[st][ed],cost);}scanf("%d%d",&s,&e);int ans=llss(s,e);printf("%d\n",ans);}
}