/* -*- coding: utf-8 -*-
 *
 * 254.cc: No.254 文字列の構成 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

/* global variables */

/* subroutines */

inline int f(int n) {
  return (2 * n - 1) + n * (n - 1) / 2 + (n - 1) * (n - 2) / 2;
}

/* main */

int main() {
  int n;
  cin >> n;

  string s;
  int ci = 0;
  while (n > 0) {
    int p, k;
    for (p = 1; (k = f(p)) <= n; p++);
    p--;

    s += (char)('a' + ci);
    for (int i = 1; i < p; i++) {
      s += (char)('a' + ci + 1);
      s += (char)('a' + ci);
    }

    n -= f(p);
    ci = (ci + 2) % 26;
  }

  cout << s << endl;
  return 0;
}