#include <bits/stdc++.h>   using namespace std;   int main() {     int n, q = 0, s = 0, t = 0;     cin >> n;     for (int k = 1; k <= n; k++) {       cin >> q;       if (q == 1) {         if (t == 1)           s++;         else {           t++;           s++;         }       } else {         if (t == 1) {           t--;           s++;         }       }     }     if (t == 0 && s != 0) s--;     cout << s;     return 0;   }   