#include<bits/stdc++.h>
using namespace std;
#define fs first
#define sc second
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define ALL(A) A.begin(),A.end()
#define RALL(A) A.rbegin(),A.rend()
typedef long long LL;
typedef pair<LL,LL> P;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
template<typename T> T gcd(T a,T b){return b?gcd(b,a%b):a;}
const LL mod=1000000007;
const LL LINF=1LL<<62;
const int INF=1<<30;
int dx[]={1,0,-1,0,1,-1,1,-1};
int dy[]={0,1,0,-1,1,-1,-1,1};


int main(){
    int n;cin >> n;
    vector<int> s(n);
    for (int i = 0; i < n; i++) {
        cin >> s[i];
    }
    vector<int> t(n);
    for (int i = 0; i < n; i++) {
        cin >> t[i];
    }
    vector<vector<int>> a(n, vector<int> (n, -1));
    for (int i = 0; i < n; i++) {
        if(s[i] == 0){
            for (int j = 0; j < n; j++) {
                a[i][j] = 0;
            }
        }
        else if(s[i] == 1){
        }
        else{
            for (int j = 0; j < n; j++) {
                a[i][j] = 1;
            }
        }
    }
    for (int i = 0; i < n; i++) {
        if(t[i] == 0){
            for (int j = 0; j < n; j++) {
                a[j][i] = 0;
            }
        }
        else if(t[i] == 1){
        }
        else{
            for (int j = 0; j < n; j++) {
                a[j][i] = 1;
            }
        }
    }
    int cs=0,ct=0;
    for (int i = 0; i < n; i++) {
        if(s[i] == 1){
            bool f = false;
            for (int j = 0; j < n; j++) {
                if(a[i][j] == 1){
                    f = true;
                    break;
                }
            }
            if(not f){
                cs++;
            }
        }
    }
    for (int i = 0; i < n; i++) {
        if(t[i] == 1){
            bool f = false;
            for (int j = 0; j < n; j++) {
                if(a[j][i] == 1){
                    f = true;
                    break;
                }
            }
            if(not f){
                ct++;
            }
        }
    }
    int ans = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            if(a[i][j] == 1) ans++;
        }
    }
    ans += max(cs, ct);
    cout << ans << endl;
    return 0;
}