#include <algorithm>
#include <cmath>
#include <cstdio>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;
using ll = long long;
int main() {
  int n;
  cin >> n;
  vector<int> s(n), t(n);
  for(int i = 0; i < n; i++) {
    cin >> s[i];
  }
  for(int i = 0; i < n; i++) {
    cin >> t[i];
  }
  int maxS = *max_element(s.begin(), s.end());
  int maxT = *max_element(t.begin(), t.end());
  if(maxS == 2 && maxT == 2) {
    cout << 2 * n - 1 << endl;
  } else if(maxS == 2) {
    int sum = 0;
    for(int i = 0; i < n; i++) {
      if(s[i] == 1) {
        sum++;
      }
    }
    cout << sum + n << endl;
  } else if(maxT == 2) {
    int sum = 0;
    for(int i = 0; i < n; i++) {
      if(t[i] == 1) {
        sum++;
      }
    }
    cout << sum + n << endl;
  } else {
    int ans = 0, sum = 0;
    for(int i = 0; i < n; i++) {
      sum += s[i];
    }
    ans = max(ans, sum);
    sum = 0;
    for(int i = 0; i < n; i++) {
      sum += t[i];
    }
    ans = max(ans, sum);
    cout << ans << endl;
  }

  return 0;
}