HDU 5050

import java.io.* ;
import java.math.* ;
import java.util.* ;
import java.text.* ;

public class Main 
{
    public static void main(String[] args) 
    {
        Scanner cin=new Scanner (new BufferedInputStream(System.in)) ;
        BigInteger A,B ;
        int t=cin.nextInt() ;
        for (int cas=1 ;cas<=t ;cas++) 
        {
            A=cin.nextBigInteger(2) ;
            B=cin.nextBigInteger(2) ;
            System.out.print("Case #"+cas+": ") ;
            System.out.println(A.gcd(B).toString(2)) ;
        }
    }
}