import java.security.MessageDigest;

public class Advent4 {

    public static String byteToHex(byte b) {
        int i = (int) b & 0xff;
        return String.format("%02x", i);
    }

    public static int countZeroes(String s) {
        int count = 0;
        for (char each : s.toCharArray()) {
            if (each == '0') {
                count++;
            } else break;
        }
        return count;
    }

    public static String byteArrayToHex(byte[] b) {
        String retval = "";
        for (byte each : b) {
            retval+= byteToHex(each);
        }
        return retval;
    }

    public static void main(String[] args) throws Exception {

        MessageDigest md = MessageDigest.getInstance("MD5");
        String test = "ckczppom";
        String temp = "";
        int count = 0;
        int pad = 1;
        while (count < 6) {
            temp = test + pad++;
            md.update(temp.getBytes());
            count = countZeroes(byteArrayToHex(md.digest()));
            md.reset();
        }
        System.out.println(temp);