#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
int n;
vector<int> a;
int main() {
  int ss = 1, i = 2;
  while (ss < N) {
    a.push_back(ss);
    ss = ss + i;
    i++;
  }
  scanf("%d", &n);
  if (n == 0) {
    puts("a");
    return 0;
  }
  string s = "";
  int w = 0;
  while (n > 0) {
    int t = upper_bound(a.begin(), a.end(), n) - a.begin() + 1;
    t--;
    n -= a[t - 1];
    for (int i = 1; i <= t + 1; i++) {
      s += char('a' + w);
    }
    w++;
  }
  cout << s << '\n';
}
