import java.util.*;
import java.io.*;
public class train2_A {

	/**
	 * @param args
	 */
	public static void main(String[] args) throws Throwable {
		Scanner r = new Scanner(new File("src/Number2_A.txt"));
		String s=r.next();
		while(!s.equals("-1"))
		{
			char c[]=s.toCharArray();
			if(s.length()==1)
			{
				System.out.println(s);
			}
			else if(s.length()==2&&c[0]==c[1])
			{
				System.out.println(s);
			}
			else if(s.length()==3&&((c[0]==c[2])||(c[0]==c[1]-1&&c[1]==c[2]-1)||(c[0]==c[1]+1&&c[1]==c[2]+1)||(c[1]==c[2]&&c[1]==0)))
			{
				System.out.println(s);
			}
			else if(s.length()==4&&((c[0]==c[2]&&c[1]==c[3])||(c[2]==c[3]&&c[2]=='0')||(c[0]==c[3]&&c[1]==c[2])||(c[0]==c[1]-1&&c[1]==c[2]-1&&c[2]==c[3]-1)||(c[0]==c[1]+1&&c[1]==c[2]+1&&c[2]==c[3]+1)))
			{
				System.out.println(s);
			}
			s=r.next();
		}


	}

}