package no254;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		StringBuilder ans = new StringBuilder();
		char c = 'a';
		while(n > 1) {
			int x = 1;
			while(x * x + x <= n) {
				x++;
			}
			x--;
			for(int i=0;i<x;i++) {
				ans.append(c);
				ans.append((char) (c+1));
			}
			n -= x * x + x;
			c = c == 'a' ? 'c' : 'a';
		}
		if (n == 1) {
			ans.append('z');
		}
		System.out.println(ans);
	}

}