#include <bits/stdc++.h>

#define rep(X, N) for (ll X = 0LL; X < (N); X++)
#define ALL(V) (V).begin(), (V).end()
#define endl "\n"

using namespace std;
typedef unsigned int uint;
typedef long long ll;
typedef unsigned long long ull;

const double PI = 3.1415926535897932384626;
const ll MODN = 1000000007;
const ll MODN2 = 998244353;

int main(){

    int n;
    cin >> n;

    vector<int> s(n), t(n);

    rep(i, n) cin >> s[i];
    rep(i, n) cin >> t[i];

    vector<vector<int>> v(n, vector<int>(n, -1));

    vector<int> row(n), col(n);
    int ans = 0;

    int c[3][3] = {{0, 0, 2}, {0, -1, 1}, {2, 1, 1}};

    rep(i, n){
        rep(j, n){
            int tmp = c[s[i]][t[j]];
            
            if(tmp == 0){

            }else if(tmp == 1){
                ans++;
                v[i][j] = 1;
                row[i]++;
                col[j]++;
            }else if(tmp == -1){

            }else{
                assert(false);
            }
        }
    }

    // Si = 1 かつ Tj = 1 かつ row[i] = 0 かつ col[j] = 0のぶぶんをうめる

    rep(i, n){
        rep(j, n){
            if(s[i] == 1 && t[j] == 1 && row[i] == 0 && col[j] == 0){
                v[i][j] = 1;
                ans++;
                row[i]++;
                col[j]++;
            }
        }
    }

    // 残りの部分を埋める

    rep(i, n){
        rep(j, n){
            if(v[i][j] == -1){
                if(s[i] == 1 && row[i] == 0){
                    v[i][j] = 1;
                    ans++;
                    row[i]++;
                    col[j]++;
                }else if(t[j] == 1 && col[j] == 0){
                    v[i][j] = 1;
                    ans++;
                    row[i]++;
                    col[j]++;
                }
            }
        }
    }

    cout << ans << endl;

    return 0;
}