#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
int a[N], b[N];
int main() {
  int m, n, k;
  m = 0;
  int sum = 0;
  for (int i = 1; a[i] <= 1e5 + 1e5; i++) {
    a[i] += a[i - 1] + i;
    m++;
  }
  cin >> k;
  if (!k) {
    cout << "a" << endl;
    return 0;
  }
  while (k) {
    for (int i = 1; i <= m && k; i++) {
      if (a[i] <= k && a[i + 1] > k) {
        k -= a[i];
        b[sum++] = i + 1;
        break;
      }
    }
  }
  for (int i = 0; i < sum; i++) {
    for (int j = 1; j <= b[i]; j++) printf("%c", 97 + i);
  }
  printf("\n");
  return 0;
}
