#include <bits/stdc++.h>
using namespace std;
int rr;
void p(int n) {
  if (n < 2) {
    rr += 0;
  } else if (n == 2) {
    rr += 1;
  } else {
    rr += (n / 2) * (n / 2 + n % 2);
    p(n / 2);
    p(n / 2 + n % 2);
  }
}
int main() {
  int n, i, j, k, l;
  char a = 'a';
  cin >> n;
  if (n == 0) {
    cout << "a";
    return 0;
  }
  for (; n > 0; a++) {
    rr = 0;
    k = 0;
    l = 2;
    while (k <= n) {
      printf("%c", a);
      rr = 0;
      p(l);
      k = rr;
      l++;
    }
    rr = 0;
    p(l - 2);
    n = n - rr;
  }
  return 0;
}
