#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
const int M = 1e6 + 10;
const int maxn = 1e6 + 10;
const int mod = 1e9 + 7;
int a[N];
int main() {
  int n, i;
  scanf("%d", &n);
  a[1] = 0;
  a[2] = 1;
  for (i = 2; a[i] <= n; i++) {
    a[i + 1] = a[i] + i;
  }
  i--;
  n -= a[i];
  int ans = 'a';
  for (int j = 0; j < i; j++) printf("%c", ans);
  ans++;
  while (n > 0) {
    int k = upper_bound(a + 1, a + i + 1, n) - a;
    k--;
    for (int j = 0; j < k; j++) printf("%c", ans);
    ans++;
    n -= a[k];
  }
  return 0;
}
