import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] counts = new int[40000];
        counts[1] = 1;
        for (int i = 2; i < 40000; i++) {
            counts[i] = counts[i - 1] + 2 + i - 1 + i - 2;
        }
        StringBuilder sb = new StringBuilder();
        int idx = 0;
        for (int i = 39999; i >= 1; i--) {
            while (n >= counts[i]) {
                n -= counts[i];
                String tmp = (char)(idx % 26 + 'a') + "" + (char)((idx + 1) % 26 + 'a');
                for (int j = 1; j < i; j++) {
                    sb.append(tmp);
                }
                sb.append((char)(idx % 26 + 'a'));
                idx += 2;
            }
        }
        System.out.println(sb);
    }
}