#include <bits/stdc++.h>
using namespace std;

vector<int> di = {-1, 0, 1, 0};
vector<int> dj = {0, 1, 0, -1};

int H = 1010, W = 1010, INF = 2000000000;

int main() {
    int n;
    cin >> n;
    vector<int> x(n), y(n);
    for (int i = 0; i < n; i++) {
        cin >> x[i] >> y[i];
    }
    int m;
    cin >> m;
    vector<int> z(m), w(m);
    for (int i = 0; i < m; i++) {
        cin >> z[i] >> w[i];
    }
    auto inc = [&](int i, int j) {
        return (0 <= i && i < H && 0 <= j && j < W);
    };
    vector<int> dist(H * W, INF);
    queue<pair<int, int>> q;
    for (int i = 0; i < n; i++) {
        dist[W * x[i] + y[i]] = 0;
        q.emplace(x[i], y[i]);
    }
    while (!q.empty()) {
        auto [i, j] = q.front();
        q.pop();
        for (int k = 0; k < 4; k++) {
            int ni = i + di[k], nj = j + dj[k];
            if (!inc(ni, nj)) {
                continue;
            }
            if (dist[W * ni + nj] > dist[W * i + j] + 1) {
                dist[W * ni + nj] = dist[W * i + j] + 1;
                q.emplace(ni, nj);
            }
        }
    }
    int ans = INF;
    for (int i = 0; i < m; i++) {
        ans = min(ans, dist[W * z[i] + w[i]]);
    }
    cout << ans << endl;
}