#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 20, inf = 0x3f3f3f3f;
long long f[N];
void init() {
  f[1] = 0;
  for (long long i = 2; i <= 700; i++) f[i] = f[i - 1] + (i - 1);
}
int ned[30];
int main() {
  init();
  memset(ned, 0, sizeof(ned));
  int k;
  cin >> k;
  for (int i = 0; i < 26; i++) {
    for (int j = 700; j >= 1; j--) {
      if (k >= f[j]) {
        k -= f[j];
        ned[i] += j;
        break;
      }
    }
  }
  for (int i = 0; i < 26; i++) {
    for (int j = 1; j <= ned[i]; j++) printf("%c", 'a' + i);
  }
  printf("\n");
  return 0;
}
