import java.io.PrintStream;
import java.io.PrintWriter;
import java.util.Scanner;


public class Main_yukicoder254 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Printer pr = new Printer(System.out);

        int n = sc.nextInt();
        StringBuilder ret = new StringBuilder();
        char base = 'a';
        
        while (n > 0) {
            int tmp = (int)Math.sqrt(n);

            if (tmp > 1) {
            	for (int i = 0; i < tmp - 1; i++) {
            		ret.append(base);
            		ret.append((char)(base + 1));
            	}
            	ret.append(base);
            	base += 2;
            	if (base > 'v') {
            		base = 'a';
            	}

            	n -= tmp * tmp;
            } else {
            	for (int i = 0; i < n; i++) {
            		ret.append(base++);
            	}
            	n = 0;
            }
        }

        pr.println(ret);

        pr.close();
        sc.close();
    }

	private static class Printer extends PrintWriter {
		Printer(PrintStream out) {
			super(out);
		}
	}
}