#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5 + 1e3;
string ans;
void solve() {
  int k;
  cin >> k;
  for (int(i) = ('a'); (i) < ('z' + 1); ++(i)) {
    ans.append(1, i);
    int tot = 1;
    while (tot <= k) {
      ans.append(1, i);
      k -= tot;
      ++tot;
    }
    if (!k) break;
  }
  cout << ans << endl;
}
int main() {
  int t = 1, ca = 0;
  while (t--) {
    solve();
  }
  return 0;
}
