#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<bitset>
#include<set>
#include<map>
#include<stack>
#include<queue>
#include<deque>
#include<list>
#include<iomanip>
#include<cmath>
#include<cstring>
#include<functional>
#include<cstdio>
#include<cstdlib>
#include<numeric>

using namespace std;

#define repr(i, a, b) for (int i = (int)(a); i < (int)(b); i++)
#define rep(i, n) repr(i, 0, n)
#define INF 2e9
//#define MOD 1000000007
#define MOD 998244353
#define LINF (long long)4e18
#define jck 3.141592

const double EPS = 1e-10;

using ll = long long;
using Pi = pair<int,int>;
using Pl = pair<ll,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];
    vector<vector<int>> a(n,vector<int>(n));
    bool s2 = false,t2 = false;
    rep(i,n){
        if(s[i] == 2){
            rep(j,n){
                a[i][j] = 1;
            }
            s2 = true;
        }
    }
    rep(i,n){
        if(t[i] == 2){
            rep(j,n){
                a[j][i] = 1;
            }
            t2 = true;
        }
    }
    vector<bool> s3(n,false),t3(n,false);
    if(!s2 && !t2){
        rep(i,n){
            if(s[i] == 1){
                rep(j,n){
                    if(t[j] == 1 && !t3[j]){
                        t3[j] = true;
                        s3[i] = true;
                        a[i][j] = 1;
                        break;
                    }
                }
            }
        }
        rep(i,n){
            if(s[i] == 1 && !s3[i]){
                rep(j,n){
                    if(t[j] == 1){
                        a[i][j] = 1;
                        break;
                    }
                }
            }
        }
        rep(j,n){
            if(!t3[j] && t[j] == 1){
                rep(i,n){
                    if(s[i] == 1){
                        a[i][j] = 1;
                        break;
                    }
                }
            }
        }
    }
    else if(s2){
        rep(i,n){
            if(s[i] == 1) a[i][0] = 1;
        }
    }
    else if(t2){
        rep(i,n){
            if(t[i] == 1) a[0][i] = 1;
        }
    }
    int ans = 0;
    rep(i,n)rep(j,n) ans += a[i][j];
    cout << ans << endl;
}