import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        StringBuilder sb = new StringBuilder();
        int idx = 0;
        for (int i = 99999; i >= 1; i--) {
            long size = (long)i * (i + 1) / 2;
            while (n >= size) {
                n -= size;
                char[] tmp = new char[i];
                Arrays.fill(tmp, (char)(idx % 26 + 'a'));
                sb.append(new String(tmp));
                idx++;
            }
        }
        System.out.println(sb);
    }
}