use std::collections::VecDeque;

use proconio::input;

const UPPER_LIMIT: usize = 3000;

const DIFFS: [(usize, usize); 4] = [(!0, 0), (0, !0), (0, 1), (1, 0)];

fn main() {
    input! {
        n: usize,
        xy: [(usize, usize); n],
        m: usize,
        zw: [(usize, usize); m],
    }

    let mut grid: Vec<Vec<Option<usize>>> = vec![vec![None; UPPER_LIMIT]; UPPER_LIMIT];
    let mut queue: VecDeque<_> = xy.iter().map(|&coord| (coord, 0_usize)).collect();
    while let Some(((x, y), dist)) = queue.pop_front() {
        if grid[x][y].is_some() {
            continue;
        }

        grid[x][y] = Some(dist);

        let adj_coords = DIFFS.iter().filter_map(|&(dx, dy)| {
            let adj_x = x.wrapping_add(dx);
            let adj_y = y.wrapping_add(dy);

            if adj_x < UPPER_LIMIT && adj_y < UPPER_LIMIT {
                Some(((adj_x, adj_y), dist + 1))
            } else {
                None
            }
        });
        queue.extend(adj_coords);
    }

    let ans = zw.iter().map(|&(z, w)| grid[z][w].unwrap()).min().unwrap();
    println!("{}", ans);
}