#include <bits/stdc++.h>
using namespace std;
const int N = 3e5;
const int M = 255;
const int INF = 0x3f3f3f3f;
const int mod = 1e9 + 7;
const double eps = 1e-6;
vector<int> v;
int n;
char p = 'a';
int main() {
  ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  ;
  cin >> n;
  if (!n) {
    cout << "a";
    return 0;
  }
  int res = 0;
  for (int i = 1; res <= n; i++) {
    res += i;
    v.push_back(res);
  }
  int sz = (int)v.size();
  for (int i = sz - 1; i >= 0; i--) {
    while (n >= v[i]) {
      n -= v[i];
      for (int j = 0; j <= i + 1; j++) cout << p;
      p++;
    }
  }
  return 0;
}
