#include<cstdio>
#include<iostream>
#include<cmath>
#include<cstring>
using namespace std;
int a[101][3];
double f[101][101];
int n,i,j,k,x,y,m,s,e;
int main()
{
    freopen("short.in","r",stdin);
    freopen("short.out","w",stdout);
    cin >> n;
    for (i = 1; i <= n; i++)
        cin >> a[i][1] >> a[i][2];
    cin >> m;
    memset(f,0x7f,sizeof(f)); 
for (i = 1; i <= m; i++)
    {
      cin >> x >> y;
      f[y][x] = f[x][y] = sqrt(pow(double(a[x][1]-a[y][1]),2)+pow(double(a[x][2]-a[y][2]),2));
}
    cin >> s >> e;
    for (k = 1; k <= n; k++)
       for (i = 1; i <= n; i++)
          for (j = 1; j <= n; j++)
             if ((i != j) && (i != k) && (j != k) && (f[i][k]+f[k][j] < f[i][j]))
                 f[i][j] = f[i][k] + f[k][j];
    printf("%.2lf\n",f[s][e]);
    return 0;
}