#include<iostream>
#include<cmath>
#include<cstring>
using namespace std;
int n,m,s,t,i,j,k,a,b;
double x[200],y[200],f[105][105],edge;
int main(){
    cin>>n;
    for(i=1;i<=n;++i)cin>>x[i]>>y[i];
    memset(f,0x7f,sizeof(f)); //初始极值
    cin>>m;
    for(i=1;i<=m;++i){
        cin>>a>>b;
        edge=sqrt((x[a]-x[b])*(x[a]-x[b])+(y[a]-y[b])*(y[a]-y[b]));
        f[a][b]=f[b][a]=edge;
    }
    cin>>s>>t;
    //注意循环嵌套 k i j 关键于最外
    for(k=1;k<=n;++k)for(i=1;i<=n;++i)for(j=1;j<=n;++j){
        if(i!=k && i!=j && k!=j && f[i][j]>f[i][k]+f[k][j]){
            f[i][j]=f[i][k]+f[k][j];    
        }  
    }
    printf("%.2f",f[s][t]);
    return 0;
}// OK