#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  int tmp = 0;
  string res;
  for (int i = 0; i < 26; i++) {
    int cnt = 0;
    for (int j = 1; j < 100; j++) {
      if (n - cnt < 0) break;
      n -= cnt;
      cnt++;
      res.push_back('a' + i);
    }
  }
  cout << res;
  return 0;
}
