#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  char x = 'a';
  putchar('z');
  while (n) {
    int inc = 1;
    while (inc * (inc - 1) / 2 <= n) inc++;
    inc--;
    n -= inc * (inc - 1) / 2;
    for (int i = 0; i < inc; i++) putchar(x);
    x++;
  }
  return 0;
}
