#include <bits/stdc++.h>
using namespace std;
const int N = 112345;
int qt[N];
int main(void) {
  ios_base::sync_with_stdio(false);
  int n;
  cin >> n;
  if (n == 0) {
    cout << 'a' << endl;
    return 0;
  }
  int st;
  qt[2] = 1;
  for (int i = 3; qt[i - 1] <= 100000; i++) {
    qt[i] = qt[i - 1] + i - 1;
    st = i;
  }
  char c = 'a';
  for (int i = st; i >= 2; i--) {
    while (qt[i] <= n) {
      for (int j = 0; j < i; j++) cout << c;
      c++;
      n -= qt[i];
    }
  }
  cout << endl;
  return 0;
}
