#include <bits/stdc++.h>
using namespace std;
int a[100009];
char now = 'a';
int n;
int main() {
  int tot = 0;
  for (int i = 1;; i++) {
    tot += i;
    if (tot > 100000) break;
    a[i] = tot;
    a[0]++;
  }
  cin >> n;
  for (int i = a[0]; i; i--) {
    while (n >= a[i]) {
      n -= a[i];
      for (int j = 0; j <= i; j++) {
        printf("%c", now);
      }
      now++;
    }
  }
  while (now <= 'z') {
    printf("%c", now);
    now++;
  }
  return 0;
}
