#include <bits/stdc++.h>
using namespace std;
int o(int t) {
    return t * t;
}
const int N = 110;
int n, m, x[N], y[N];
double g[N][N];

int main() {
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> x[i] >> y[i];

    // double类型的数组，初始化不能用memset!!!!
    // memset(g, 0x3f, sizeof g);
    //  for (int i = 0; i <= n; i++) g[i][i] = 0;

    // 需要用二重循环进行初始化
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= n; j++) {
            if (i == j)
                g[i][j] = 0;
            else
                g[i][j] = 0x3f3f3f3f;
        }

    cin >> m;
    int l, r;
    while (m--) {
        cin >> l >> r;
        g[r][l] = g[l][r] = sqrt((double)o(x[l] - x[r]) + (double)o(y[l] - y[r])); // 勾股定理
    }

    // floyd
    for (int k = 1; k <= n; k++)
        for (int i = 1; i <= n; i++)
            for (int j = 1; j <= n; j++)
                if (g[i][j] > g[i][k] + g[k][j]) g[i][j] = g[i][k] + g[k][j];

    cin >> l >> r;
    printf("%.2lf", g[l][r]);
    return 0;
}