#include <bits/stdc++.h>
using namespace std;
int main() {
  srand(time(NULL));
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.setf(ios::fixed);
  cout.precision(0);
  long long n;
  cin >> n;
  string s;
  char y = 'a';
  while (n != 0) {
    s.push_back(y);
    int t = 1;
    while (t <= n) {
      s.push_back(y);
      n -= t;
      t++;
    }
    y++;
  }
  if (s.size() == 0) s.push_back('a');
  cout << s;
}
