#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
#define inf 99999
int main()
{
	freopen("rebuild.in","r",stdin);
	freopen("rebuild.out","w",stdout);
	int a[110][110]={0},b[110][110]={0},n,m,d,x,y,v;
	cin>>n>>m;
	for(int i=1;i<=n;i++)
		for(int j=1;j<=n;j++)
			a[i][j]=inf,b[i][j]=inf;
	for(int i=1;i<=m;i++)
	{
		cin>>x>>y>>v;
		a[x][y]=min(a[x][y],v);
		a[y][x]=min(a[y][x],v);
		b[x][y]=b[y][x]=0;
	}
	cin>>d;
	for(int i=1;i<=d;i++)
	{
		cin>>x>>y;
		b[x][y]=a[x][y];
		b[y][x]=a[y][x];
	}
	for(int k=1;k<=n;k++)
		for(int i=1;i<=n;i++)
			for(int j=1;j<=n;j++)
			{
				if(b[i][j]>b[i][k]+b[k][j])
				{
					b[i][j]=b[i][k]+b[k][j];
				}
			}
	int p,q;
	cin>>p>>q;
	cout<<b[p][q]<<endl;
	return 0;
}