#include <bits/stdc++.h>
using namespace std;
int n, sum;
int main() {
  cin >> n;
  for (char i = 'a'; i <= 'z'; ++i) {
    for (int j = 0; (sum + j) <= n; sum += j++) {
      cout << i;
    }
  }
  cout << '\n';
  return 0;
}
