#include <bits/stdc++.h>
using namespace std;
int k;
int used[256];
void print() {
  for (int i = 'a'; i <= 'z'; i++) {
    for (int j = 1; j <= used[i]; j++) cout << (char)i;
  }
}
bool visited[100005][27];
bool dp[100005][27];
bool solve(int sum, char cur) {
  if (sum > k || cur > 'z') return false;
  if (sum == k) {
    print();
    exit(0);
    return true;
  }
  if (visited[sum][cur - 'a']) return dp[sum][cur - 'a'];
  visited[sum][cur - 'a'] = true;
  bool ans = false;
  for (int j = 2; j <= 317; j++) {
    used[cur] = j;
    ans |= solve(sum + ((j * (j - 1)) / 2), cur + 1);
    used[cur] = 0;
  }
  return dp[sum][cur - 'a'] = ans;
}
int main() {
  cin >> k;
  if (k == 0) {
    cout << "a";
    return 0;
  }
  solve(0, 'a');
  return 0;
}
