UVA Problem ID 11723 (Numbering Roads)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;


public class Main {
	public static void main (String args[]) throws IOException
	{
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb=new StringBuilder(1000);
		int testcase=0;
		while(true)
		{
			testcase++;
			String s[]=br.readLine().split(" +");
			int R=Integer.parseInt(s[0]);
			int N=Integer.parseInt(s[1]);
			if(R==0 && N==0)
				break;
			int a=R-N;
			int ans;
			if(a%N==0 || R26)
				sb.append("Case "+testcase+": impossible\n");
			else
				sb.append("Case "+testcase+": "+ans+"\n");
		}
		System.out.print(sb);
	}
}