func_code_string: #include <bits/stdc++.h>   using namespace std;   const long double pi = acos(-1);   const long long M = 1e9 + 7;   const long long N = 5e5;   const long long INF = 1e9 + 1;   long long n, a[N], x[N], res, ans;   int main() {     cin >> n;     for (int i = 1; i <= n; ++i) {       cin >> a[i];     }     for (int j = 1; j <= n; ++j) {       for (int i = 1; i <= n; ++i) {         if (x[i] != 1 && ans >= a[i]) {           x[i] = 1;           ans++;         }       }       if (ans == n) {         break;       }       res++;       for (int i = n; i >= 1; --i) {         if (x[i] != 1 && ans >= a[i]) {           x[i] = 1;           ans++;         }       }       if (ans == n) {         break;       }       res++;     }     cout << res;     return 0;   }   