#include <bits/stdc++.h>
using namespace std;
const int maxn = 100;
int n;
int main() {
  scanf("%d", &n);
  int tot = 0;
  int zhi = 0;
  for (int zhi = 0; zhi < 26; ++zhi) {
    for (int i = 0; tot + i <= n; ++i) {
      if (tot + i <= n) tot += i;
      printf("%c", 'a' + zhi);
      if (tot == n) return 0;
    }
  }
  return 0;
}
