#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define repr(i,n) for(int i = (int)(n); i >= 0; i--)
#define all(v) v.begin(),v.end()
typedef long long ll;

int main(){
    int N;
    cin >> N;
    vector<int> S(N), T(N);
    rep(i,N){
        cin >> S[i];
    }
    rep(i,N){
        cin >> T[i];
    }
    int gyoumin = 0;
    int retsumin = 0;
    rep(i,N){
        if (S[i] == 1) gyoumin += 1;
        if (S[i] == 2) gyoumin += N;
    }
    rep(i,N){
        if (T[i] == 1) retsumin += 1;
        if (T[i] == 2) retsumin += N;
    }
    vector<vector<bool> > locked(N, vector<bool> (N));
    rep(i,N){
        rep(j,N){
            locked[i][j] = false;
        }
    }
    rep(i,N){
        if (S[i] == 2){
            rep(j,N){
                locked[i][j] = true;
            }
        }
    }
    rep(j,N){
        if (T[j] == 2){
            rep(i,N){
                locked[i][j] = true;
            }
        }
    }
    int lockmin = 0;
    rep(i,N){
        rep(j,N){
            if (locked[i][j]) lockmin++;
        }
    }
    cout << max(gyoumin, max(retsumin, lockmin)) << endl;
}