#include<bits/stdc++.h>
using namespace std;
struct node
{
    int start,reach,weight,cost,next;
}edge[5005];
struct again
{
    int pos,dis;
    friend bool operator<(again a,again b)
    {
        return a.dis>b.dis;
    }
};
int n,m,tot=0,head[105],dis[105];
bool f[105];
void add(int u,int v,int w,int t)
{
    edge[tot].start=u;edge[tot].reach=v;
    edge[tot].weight=w;edge[tot].cost=t;
    edge[tot].next=head[u];
    head[u]=tot;
}
void dijkstra(int begin)
{
    priority_queue<again>que;
    again temp;
    for (int i=1;i<=n;++i) dis[i]=2147483647;
    temp.pos=begin;temp.dis=0;dis[begin]=0;f[begin]=true;
    que.push(temp);
    while (!que.empty())
    {
        again tmp=que.top();
        que.pop();
        for (int i=head[tmp.pos];i!=0;i=edge[i].next)
            if (f[edge[i].reach]==false&&dis[tmp.pos]+edge[i].cost<dis[edge[i].reach])
            {
                f[edge[i].reach]=true;
                dis[edge[i].reach]=dis[tmp.pos]+edge[i].cost;
                again t;
                t.pos=edge[i].reach;t.dis=dis[edge[i].reach];
                que.push(t);
            }
    }
}
int main()
{
    int a,b,l,d,x,y;
    cin>>n>>m;
    for (int i=1;i<=m;++i)
    {
        cin>>a>>b>>l;
        ++tot;add(a,b,l,0);
        ++tot;add(b,a,l,0);
    }
    cin>>d;
    for (int i=1;i<=d;++i)
    {
        cin>>x>>y;
        for (int j=head[x];j!=0;j=edge[j].next)
            if (edge[j].reach==y)
            {
                edge[j].cost=edge[j].weight;break;
            }
        for (int j=head[y];j!=0;j=edge[j].next)
            if (edge[j].reach==x)
            {
                edge[j].cost=edge[j].weight;break;
            }
    }
    cin>>x>>y;
    dijkstra(x);
    cout<<dis[y];
    return 0;
}