#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define ALL(v) v.begin(),v.end()
#define dbg(x) cerr << #x << ": " << (x) << endl;
#define MAX (1000)
int N,M;
vector<bitset<MAX>> P(MAX),Q(MAX);
int main() {
    cin >> N;
    for (int i = 0; i < N; ++i) {
        int x,y; cin >> x >> y;
        P[y].set(x);
    }
    cin >> M;
    for (int i = 0; i < N; ++i) {
        int x,y; cin >> x >> y;
        Q[y].set(x);
    }
    int ans = 1e9;
    vector dp(MAX, vector<int>(MAX, 1e9));
    for (int i = 0; i < MAX; ++i) {
        for (int j = 0; j < MAX; ++j) {
            if (i > 0) dp[i][j] = min(dp[i][j], dp[i-1][j] + 1);
            if (j > 0) dp[i][j] = min(dp[i][j], dp[i][j-1] + 1);
            if (Q[i].test(j)) {
                dp[i][j] = 0;
            }
            if (P[i].test(j)) {
                ans = min(ans, dp[i][j]);
            }
        }
    }
    for (int i = 0; i < MAX; ++i) {
        for (int j = 0; j < MAX; ++j) {
            dp[i][j] = 1e9;
        }
    }
    for (int i = MAX-1; i >= 0; --i) {
        for (int j = MAX-1; j >= 0; --j) {
            if (i < MAX-1) dp[i][j] = min(dp[i][j], dp[i+1][j] + 1);
            if (j  < MAX-1) dp[i][j] = min(dp[i][j], dp[i][j+1] + 1);
            if (Q[i].test(j)) {
                dp[i][j] = 0;
            }
            if (P[i].test(j)) {
                ans = min(ans, dp[i][j]);
            }
        }
    }
    cout << ans << '\n';
}