#include <bits/stdc++.h>
using namespace std;
string solve(int &a, char cur) {
  int left = 'z' - cur + 1;
  if (a <= left) {
    string re = "";
    while (a > 0) {
      a--;
      re += cur;
      cur++;
    }
    return re + re;
  }
  long long cnt = 1;
  long long tot = 0;
  while (tot < a) {
    cnt++;
    tot = cnt * (cnt - 1) / 2;
  }
  if (tot > a) cnt--;
  tot = cnt * (cnt - 1) / 2;
  a -= tot;
  string ree(cnt, cur);
  return ree;
}
long long verify(string &a, long long k) {
  map<char, int> all;
  long long re = 0;
  for (char i : a) {
    re += all[i];
    all[i]++;
  }
  return re == k;
}
string solvee(int k) {
  if (k == 0) return "a";
  char cur = 'a';
  string re = "";
  while (k > 0) {
    re += solve(k, cur);
    cur++;
  }
  return re;
}
int main() {
  int k;
  cin >> k;
  cout << solvee(k);
}
