#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (int)n; i++)
using ll = long long;

int main(){
  int n;
  cin >> n;
  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,-1));
  rep(i,n) {
    if(s[i] == 0) rep(j,n) a[i][j] = 0;
    if(s[i] == 2) rep(j,n) a[i][j] = 1; 
    if(t[i] == 0) rep(j,n) a[j][i] = 0;
    if(t[i] == 2) rep(j,n) a[j][i] = 1;
  }
  rep(i,n) {
    rep(j,n) {
      if(a[i][j] == -1 and s[i] == 1 and t[j] == 1) {
        a[i][j] = 1;
        rep(k,n) if(a[i][k] == -1) a[i][k] = 0;
        rep(k,n) if(a[k][j] == -1) a[k][j] = 0;
      }
    }
  }
  int ans = 0;
  rep(i,n) rep(j,n) if(a[i][j] == -1 or a[i][j] == 1) ans++;
  cout << ans << endl;
  return 0;
}