#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 x = 0;
    int y = 0;
    int cnt = 0;
    int t[N]{};
    int u[N]{};
    vector<int> v, w;
    for (int i = 0; i < N; i++) {
        bool f1 = true;
        bool f2 = true;
        if (S[i] != 1) f1 = false;
        if (T[i] != 1) f2 = false;
        for (int j = 0; j < N; j++) {
            if (A[i][j] == 1) f1 = false;
            if (A[j][i] == 1) f2 = false;
        }
        if (f1) x++;
        if (f2) y++;
    }

    cnt = max(x, y);
    //cout << x << " " << y << "\n";
    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;
}