#include<bits/stdc++.h>
using namespace std;
//#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
#define vec vector<ll>
#define mat vector<vector<ll> >
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
typedef long double ld;
typedef complex<double> comp;
const ll INF=1e9+7;
const ll MOD=998244353;
const int MAX=200010;


signed main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll n;cin>>n;
    vector<vector<ll> >a(n,vector<ll>(n));
    vector<ll>s(n);
    vector<ll>t(n);
    rep(i,n)cin>>s[i];
    rep(i,n)cin>>t[i];
    ll z=0,y=0;
    ll cnt1=0,cnt0=0;
    rep(i,n){
        if(s[i]==2){
            z=1;
            rep(j,n){
                a[i][j]=1;
            }
        }else if(s[i]==1){
            cnt1++;
        }
        if(t[i]==2){
            rep(j,n){
                a[j][i]=1;
            }
            y=1;
        }else if(t[i]==1){
            cnt0++;
        }
    }
    ll ans=0;
    rep(i,n){
        rep(j,n){
            ans+=a[i][j];
        }
    }
    if(z){
        if(y){
        }else{
            ans+=cnt1;
        }
    }else{
        if(z)ans+=cnt0;
        else ans+=max(cnt0,cnt1);
    }
    cout<<ans<<endl;
}