import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayDeque;
import java.util.Queue;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		int mx = 1000;
		int[][] d = new int[mx][mx];
		Queue<Integer> que = new ArrayDeque<>();
		for (int i = 0; i < n; i++) {
			String[] sa = br.readLine().split(" ");
			int x = Integer.parseInt(sa[0]);
			int y = Integer.parseInt(sa[1]);
			d[x][y] = 1;
			que.add(x * mx + y);
		}

		boolean[][] g = new boolean[mx][mx];
		int m = Integer.parseInt(br.readLine());
		for (int i = 0; i < m; i++) {
			String[] sa = br.readLine().split(" ");
			int z = Integer.parseInt(sa[0]);
			int w = Integer.parseInt(sa[1]);
			g[z][w] = true;
		}
		br.close();

		int[] dx = {1, 0, -1, 0};
		int[] dy = {0, 1, 0, -1};
		while (!que.isEmpty()) {
			int cur = que.poll();
			int cx = cur / mx;
			int cy = cur % mx;
			if (g[cx][cy]) {
				System.out.println(d[cx][cy] - 1);
				return;
			}
			for (int i = 0; i < 4; i++) {
				int nx = cx + dx[i];
				int ny = cy + dy[i];
				if (nx < 0 || mx <= nx || ny < 0 || mx <= ny) {
					// g[nx][ny] == '#' みたいな条件もあれば
					continue;
				}
				int next = nx * mx + ny;
				if (d[nx][ny] == 0) {
					que.add(next);
					d[nx][ny] = d[cx][cy] + 1;
//					if (g[nx][ny]) {
//						System.out.println(d[nx][ny] - 1);
//						return;
//					}
				}
			}
		}
	}
}