func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     long long n;     cin >> n;     long long a[n];     for (long long i = 0; i < n; i++) cin >> a[i];     long long ans = 0;     for (long long i = n - 1; i >= 0; i--) {       if (i == n - 1)         ans += a[i];       else if (a[i] < a[i + 1])         ans += a[i];       else if (a[i] >= a[i + 1]) {         if (a[i + 1] == 0)           a[i] = 0;         else {           ans += a[i + 1] - 1;           a[i] = a[i + 1] - 1;         }       }     }     cout << ans;     return 0;   }   