_,W,_,B=[set(map(int,input().split())) for _ in [0]*4]
w,b,c=1,1,0
for x in sorted(list(W|B)):
	if x in W&B:c+=1;w,b=b,w
	elif b*x in W:c+=1;w,b=1,0
	elif w*x in B:c+=1;w,b=0,1
print(c)