#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, i, j = 0, k;
  char l = 'a';
  cin >> n;
  if (n == 0) {
    cout << "a\n";
    return 0;
  }
  for (i = 1000; i > 0 && n; i--)
    while ((i * (i + 1)) / 2 <= n) {
      n -= (i * (i + 1)) / 2;
      for (k = 0; k <= i; k++) cout << l;
      l++;
    }
  cout << endl;
  return 0;
}
