func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     int a[1000000];     for (int i = 0; i < n; i++) {       cin >> a[i];     }     int cur = a[n - 1];     long long total = a[n - 1];     for (int i = n - 2; i >= 0; i--) {       cur = min(cur - 1, a[i]);       cur = max(0, cur);       total += cur;     }     cout << total;     return 0;   }   