func_code_string: #include <bits/stdc++.h>   using namespace std;   const long double PI = atan(1.0) * 4.0;   const long long int MOD = 1e9 + 7;   const long long int INF = 1e5;   const long double EPS = 0.0000001;   int main() {     ios_base::sync_with_stdio(false), cin.tie(NULL);     int a[1005], k;     a[0] = -1;     a[1] = 0;     for (int i = 2; i <= 1005; i++) {       a[i] = a[i - 1] + i - 1;     }     cin >> k;     if (k == 0) {       cout <<  a  << endl;       return 0;     }     char ch =  a ;     while (k > 0) {       int lb = lower_bound(a, a + 1005, k) - a;       if (a[lb] != k) lb--;       for (int i = 1; i <= lb; i++) cout << ch;       k -= a[lb];       ch++;     }     cout << endl;     return 0;   }   