from collections import deque

N = int(input())
S = [tuple(map(int, input().split())) for _ in range(N)]
M = int(input())
T = [tuple(map(int, input().split())) for _ in range(M)]
G, I = 1000, float('inf')
dS, dT = [[I]*G for _ in range(G)], [[I]*G for _ in range(G)]
qS, qT = deque(S), deque(T)
for x, y in S: dS[x][y] = 0
for x, y in T: dT[x][y] = 0
def bfs(q, d):
    while q:
        x, y = q.popleft()
        for dx, dy in [(-1,0), (1,0), (0,-1), (0,1)]:
            nx, ny = x+dx, y+dy
            if 0<=nx<G and 0<=ny<G and d[nx][ny]==I:
                d[nx][ny] = d[x][y] + 1
                q.append((nx, ny))
bfs(qS, dS)
bfs(qT, dT)
print(min(dS[x][y] + dT[x][y] for x in range(G) for y in range(G)))