UVA - 10790 - How Many Points of Intersection?

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));
        StringBuffer sb = new StringBuffer("");
        int i=1;
        while (true) {
            String[] str=br.readLine().split(" ");
            long x = Integer.parseInt(str[0]);
            long y =Integer.parseInt(str[1]);
            if(x==0 &&y==0)
                break;
            sb.append("Case ").append(i).append(": ");
            sb.append(x*y*(y-1)*(x-1)/4).append("\n");
            i++;
        }
        System.out.print(sb);
    }
}