#include<bits/stdc++.h>
using namespace std;
const int inf=99999999;
int n;
int dis[110][110];
int m;
int c[110][110];
int a,b;
int main(){
	freopen("rebuild.in","r",stdin);
	freopen("rebuild.out","w",stdout);
	cin>>n>>m;
	for(int i=1;i<=n;++i)
	    for(int j=1;j<=n;++j)
	        if(i!=j)dis[i][j]=c[i][j]=inf;
	for(int i=1;i<=m;++i)
          {
		int x,y,z;
		cin>>x>>y>>z;
		c[x][y]=c[y][x]=z;
	}
	cin>>m;
	for(int i=1;i<=m;++i)
       {
		int x,y;
		cin>>x>>y;
		dis[x][y]=dis[y][x]=c[x][y];
	}
	cin>>a>>b;
	for(int i=1;i<=n;++i)
	    for(int j=1;j<=n;++j)
	        if(dis[i][j]==inf&&c[i][j]<inf)dis[i][j]=0;
	for(int k=1;k<=n;++k)
	 for(int i=1;i<=n;++i)
	 for(int j=1;j<=n;++j)
	     if(i!=j&&i!=k&&j!=k)
	  dis[i][j]=min(dis[i][k]+dis[k][j],dis[i][j]);
	cout<<dis[a][b];
	return 0;
}