func_code_string: #include <bits/stdc++.h>   using namespace std;   signed main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     int n;     cin >> n;     vector<int> a(n);     for (int &i : a) cin >> i;     int ans = -1, now = 0;     vector<bool> vis(n);     while (now < n) {       ans++;       if (ans % 2)         for (int i = n - 1; i >= 0; i--)           if (!vis[i] && a[i] <= now)             vis[i] = true, now++;           else             ;       else         for (int i = 0; i < n; i++)           if (!vis[i] && a[i] <= now)             vis[i] = true, now++;           else             ;     }     cout << ans <<   n ;     return 0;   }   