#include <bits/stdc++.h>
int dx[] = {-1, -1, -1, 0, 1, 1, 1, 0};
int dy[] = {-1, 0, 1, 1, 1, 0, -1, -1};
using namespace std;
long long power(long long a, long long p, long long M) {
  long long r = 1;
  a = a % M;
  while (p > 0) {
    if (p % 2) r = (r * a) % M;
    a = (a * a) % M;
    p /= 2;
  }
  return r;
}
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
void solve() {
  int n;
  cin >> n;
  string ans = "z";
  int x = 0;
  while (n) {
    int j;
    for (int i = 1; i < 1000; i++) {
      if (n < i * (i - 1) / 2) {
        j = i;
        break;
      }
    }
    j--;
    n -= j * (j - 1) / 2;
    for (int i = 0; i < j; i++) {
      ans += (x + 'a');
    }
    x++;
  }
  cout << ans << endl;
}
int main() {
  solve();
  return 0;
}
