#include <bits/stdc++.h>
using namespace std;
long long int helper(long long int n) {
  long long int ans = 0, s = 1, e = 2000;
  while (s <= e) {
    long long int mid = (s + e) / 2;
    long long int a = (mid * (mid + 1)) / 2;
    if (a <= n) {
      ans = mid;
      s = mid + 1;
    } else
      e = mid - 1;
  }
  return ans;
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int n;
  cin >> n;
  long long int k = n;
  if (n == 0) {
    cout << "a";
    return 0;
  }
  vector<long long int> ans;
  while (k > 0) {
    long long int a = helper(k);
    ans.push_back(a + 1);
    k = k - ((a * (a + 1)) / 2);
  }
  for (long long int i = 0; i < ans.size(); i++) {
    for (long long int j = 0; j < ans[i]; j++) {
      char c = 'a' + i;
      cout << c;
    }
  }
  return 0;
}
