#include <bits/stdc++.h>
using namespace std;
int t[1000];
int main() {
  t[2] = 1;
  int n, i;
  cin >> n;
  if (n == 0) {
    cout << "a";
    return 0;
  }
  for (i = 3; t[i - 1] < n; ++i) {
    t[i] = t[i - 1] + i - 1;
  }
  int j = i - 1;
  for (char c = 'a'; c <= 'z'; ++c) {
    if (!n) break;
    while (t[j] > n) --j;
    n -= t[j];
    for (int k = 0; k < j; ++k) cout << c;
  }
  cout << endl;
  return 0;
}
