#include <bits/stdc++.h>
using namespace std;
long long int n, t;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n;
  long long int f[26] = {0}, x = 0;
  while (n > 1) {
    int j = 0, sum = 0;
    while (sum + j + 2 <= n) j = j + 2, sum += j;
    f[x++] = (j - 2) / 2 + 2;
    f[x++] = (j - 2) / 2 + 2;
    n -= sum;
  }
  if (n == 1) {
    f[x++] = 2;
  }
  long long int flag = 0;
  for (int i = 0; i < x; i++) {
    char c = i + 97;
    while (f[i]) cout << c, f[i]--, flag = 1;
  }
  if (flag == 0) cout << 'x';
}
