#include <bits/stdc++.h>
using namespace std;
const int N = 100000;
int choose2(int n);
int smallest(const vector<int>& chooses, int n);
int main() {
  vector<int> chooses;
  for (int i = 0; choose2(i) < N; i++) chooses.push_back(choose2(i));
  int n;
  while (cin >> n) {
    string ret;
    char next = 'a';
    while (n > 0) {
      int use = smallest(chooses, n);
      ret += string(use, next++);
      n -= choose2(use);
    }
    if (ret.size() == 0) ret += next;
    cout << ret << '\n';
  }
}
int choose2(int n) { return n * (n - 1) / 2; }
int smallest(const vector<int>& chooses, int n) {
  if (chooses.back() <= n) return chooses.size() - 1;
  for (int i = 0; i < chooses.size(); i++)
    if (chooses[i] > n) return i - 1;
  assert(false);
}
