#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e16;
const double EPS = 1e-16;
const long long MOD = (long long)(1000000007);
const long long MAXV = (long long)(1e5 + 10);
const long long MAXE = (long long)(1e6 + 10);
int n;
int main() {
  cin >> n;
  char curr = 'b';
  cout << "a";
  while (n) {
    int a = 1;
    while (a * (a + 1) <= n * 2) a++;
    a--;
    for (int i = 0; i <= a; i++) cout << curr;
    curr++;
    n -= (a * (a + 1)) / 2;
  }
  cout << "\n";
}
