n = int(input())
s = list(map(int, input().split()))
t = list(map(int, input().split()))


a = [[-1] * n for i in range(n)]
for i in range(n):
    if s[i] == 0:
        for j in range(n):
            a[i][j] = 0
    if s[i] == 2:
        for j in range(n):
            a[i][j] = 1
    if t[i] == 0:
        for j in range(n):
            a[j][i] = 0
    if t[i] == 2:
        for j in range(n):
            a[j][i] = 1

cnt1 = 0
for i in range(n):
    for j in range(n):
        if a[i][j] == 1:
            cnt1 += 1

if 2 in s and 2 in t:
    print(cnt1)
elif 0 in s and 0 in t:
    print(max(s.count(1), t.count(1)))
else:
    print(cnt1 + min(s.count(1), t.count(1)))