#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main() {
    int N;
    cin >> N;
    int S[N], T[N];
    for (int i = 0; i < N; i++) {
        cin >> S[i];
    }
    for (int i = 0; i < N; i++) {
        cin >> T[i];
    }
    int A[N][N]{};
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            A[i][j] = -1;
        }
    }
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            if (S[i] == 2) A[i][j] = 1;
            if (T[i] == 2) A[j][i] = 1;
            if (S[i] == 0) A[i][j] = 0;
            if (T[i] == 0) A[j][i] = 0;
        }
    }
    int cnt = 0;
    int t[N]{};
    int u[N]{};
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            if (A[i][j] == -1) {
                t[i]++;
                u[j]++;
            }
        }
    }
    int x = 0;
    int y = 0;
    for (int i = 0; i < N; i++) {
        if (t[i] != 0) x++;
        if (u[i] != 0) y++;
    }
    cnt = min(x, y);
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            if (A[i][j] == 1) cnt++;
            //cout << A[i][j] << " ";
        }
        //cout << "\n";
    }
    cout << cnt << "\n";
    return 0;
}