#include <bits/stdc++.h>
using namespace std;
using ll = long long;
void dout() { cerr << endl; }
template <typename Head, typename... Tail>
void dout(Head H, Tail... T) {
  cerr << H << ' ';
  dout(T...);
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int k;
  cin >> k;
  vector<int> a(26);
  string ans;
  for (int i = 0; i < 26; i++) {
    int s = 0;
    for (int j = 0; s + j <= k; j++) {
      s += j;
      ans += char('a' + i);
    }
    k -= s;
    if (k == 0) break;
  }
  cout << ans;
  return 0;
}
