import queue
I,R=input,range
J=lambda:map(int,I().split())
H=1000
N=int(I())
t=H*H
L=t+1
D=[-1]*L
V=queue.Queue()
for i in R(N):
	x,y=J()
	u=x*H+y
	D[u]=0
	V.put(u)
M=int(I())
T=[0]*L
for j in R(M):
	z,w=J()
	T[z*H+w]=1
while V.qsize():
	u=V.get()
	i,j=u//H,u%H
	E=[]
	if u<t:
		if i:E+=[u-H]
		if i+1<H:E+=[u+H]
		if j:E+=[u-1]
		if j+1<H:E+=[u+1]
		if T[u]:E+=[t]
	for v in E:
		if D[v]<0:
			D[v]=D[u]+1
			V.put(v)
print(D[t]-1)