#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#include <iomanip>
#include <cmath>

class DSU {
    std::vector<int> dsu;
    std::vector<int> sizes;

public:
    DSU(int n) {
        for (int i = 0; i < n; ++i) {
            dsu.push_back(i);
        }
        sizes.resize(n, 1);
    }

    int find_root(int a) {
        if (dsu[a] == a) {
            return a;
        }
        return dsu[a] = find_root(dsu[a]);
    }

    void union_dsu(int a, int b) {
        if (sizes[b] < sizes[a]) {
            dsu[b] = a;
            sizes[a] += sizes[b];
        } else {
            dsu[a] = b;
            sizes[b] += sizes[a];
        }
    }


};

int main() {
    int N;
    std::cin >> N;
    int a, b;
    std::vector<std::vector<double>> matrix(N, std::vector<double>(N, 0));
    std::vector<std::pair<int, int>> points(N);
    for (int i = 0; i < N; ++i) {
        std::cin >> a >> b;
        points[i] = std::make_pair(a, b);
    }
    double s;
    for (int i = 0; i < N; ++i) {
        for (int j = i + 1; j < N; ++j) {
            s = std::pow(std::pow(points[i].first - points[j].first, 2) + std::pow(points[i].second - points[j].second, 2), 0.5);
            matrix[i][j] = s;
        }
    }
    int M;
    std::cin >> M;
    for (int i = 0; i < M; ++i) {
        std::cin >> a >> b;
        matrix[a - 1][b - 1] = 0;
        matrix[b - 1][a - 1] = 0;
    }
    std::vector<std::pair<double, std::pair<int, int>>> lines;
    for (int i = 0; i < N; ++i) {
        for (int j = i + 1; j < N; ++j) {
            lines.push_back(std::make_pair(matrix[i][j], std::make_pair(i, j)));
        }
    }
    DSU dsu(N);
    std::sort(lines.begin(), lines.end());
    double answer = 0;
    for (int i = 0; i < lines.size(); ++i) {
        double s = lines[i].first;
        int a = lines[i].second.first;
        int b = lines[i].second.second;
        int r1 = dsu.find_root(a);
        int r2 = dsu.find_root(b);
        if (r1 != r2) {
            answer += s;
            dsu.union_dsu(r1, r2);
        }
    }
    std::cout << std::setprecision(5) << answer << '\n';
}