#include <bits/stdc++.h>
using namespace std;
const double PI = acos(-1.0);
const double eps = 1e-11;
const long long INF = 0x3f3f3f3f3f3f3f3f;
int a[100005];
int main() {
  a[1] = 0;
  a[2] = 1;
  a[3] = 3;
  for (int i = 4;; i++) {
    if (i % 2)
      a[i] = a[i / 2] + a[i / 2 + 1] + i / 2 * (i / 2 + 1);
    else
      a[i] = 2 * a[i / 2] + i / 2 * (i / 2);
    if (a[i] > 100000) {
      break;
    }
  }
  int k;
  int ans[500], cs = 0;
  scanf("%d", &k);
  if (k == 0) {
    printf("a");
    return 0;
  }
  for (int i = 448; k != 0; i--)
    if (a[i] <= k) {
      ans[cs++] = i;
      k -= a[i];
      if (a[i] <= k) i++;
    }
  for (int i = 0; i < cs; i++)
    for (int j = 0; j < ans[i]; j++) printf("%c", 'a' + i);
  return 0;
}
