/* -*- coding: utf-8 -*-
 *
 * 600.cc: No.600 かい文回 - 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 */

typedef vector<int> vi;
typedef stack<int> si;

/* global variables */

/* subroutines */

/* main */

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

  if (n == 1) {
    puts("a");
    return 0;
  }

  si q;
  while (n) {
    q.push(n & 1);
    n >>= 1;
  }    
  //while (! q.empty()) printf("%d", q.top()), q.pop(); putchar('\n');

  int p = 0;
  vi v;
  q.pop();
  while (! q.empty()) {
    int d = q.top(); q.pop();
    v.push_back(p);
    if (d == 1) p = (p + 1) % 26, v.push_back(p);
  }

  for (int i = v.size() - 1; i >= 0; i--) putchar(v[i] + 'a');
  for (int i = 0; i < v.size(); i++) putchar(v[i] + 'a');
  putchar('\n');

  return 0;
}