#include<bits/stdc++.h>
using namespace std;
int n,m,s,t,h[105],l[105];double dis[105];bool vis[105];
struct st{int v;double w;};
vector<st>e[2005];
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++)
		cin>>h[i]>>l[i];
	cin>>m;
	for(int i=1;i<=n;i++)
	{
		int u,v;double w;
		cin>>u>>v;
		w=sqrt((h[u]-h[v])*(h[u]-h[v])+(l[u]-l[v])*(l[u]-l[v]));
		e[u].push_back({v,w});
		e[v].push_back({u,w});
	}
	cin>>s>>t;
	for(int i=1;i<=n;i++)
		dis[i]=1e3+1;
	dis[s]=0;
	for(int i=1;i<=n;i++)
	{
		double minn=1e3+1;int u;
		for(int i=1;i<=n;i++)
			if(dis[i]<minn&&vis[i]==0)
				minn=dis[i],u=i;
		vis[u]=1;
		int len=e[u].size();
		for(int j=0;j<len;j++)
			dis[e[u][j].v]=min(dis[e[u][j].v],dis[u]+e[u][j].w);
	}
	printf("%.2lf",dis[t]);
	return 0;
}