#include <bits/stdc++.h>
using namespace std;

int n;

string solve();

int main() {
  cin >> n;
  cout << solve() << endl;
  return 0;
}

string solve() {
  string res = "z";
  int nxt = 0;
  for(int i = 62 - __builtin_clzll(n); i >= 0; --i) {
    res = res[0] + res + res[0];
    if(n >> i & 1) {
      string tmp;
      tmp += (char)('a' + nxt);
      res = tmp + res + tmp;
      (++nxt) %= 26;
    }
  }
  return res;
}