#include <bits/stdc++.h>
void solve(int n, char x = 'a') {
  printf("%c", x);
  for (int i = 1, s = 0; n - i >= 0; n -= (i++)) {
    printf("%c", x);
  }
  if (n > 0) solve(n, x + 1);
}
int main() {
  int n;
  scanf("%d", &n);
  solve(n);
  return 0;
}
