#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 9;
int main() {
  int n;
  int arr[maxn];
  arr[1] = 0, arr[2] = 1;
  for (int i = 3; i <= 1000; i++) {
    arr[i] = arr[i / 2] + arr[i - i / 2] + i / 2 * (i - i / 2);
  }
  int num[26];
  while (cin >> n) {
    for (int i = 0; i < 26; i++) num[i] = 1;
    int e = 1;
    while (num[e] <= n) e++;
    int no = 0;
    while (n > 0) {
      if (arr[e] <= n) {
        n -= arr[e];
        num[no++] = e;
      } else {
        e--;
      }
    }
    for (int i = 0; i < 26; i++) {
      for (int j = 0; j < num[i]; j++) cout << char('a' + i);
    }
    cout << endl;
  }
}
