View Code of Problem 3689

import java.util.*;
import java.math.BigInteger;;
public class Main {
	
	public static void main(String[] args) {
		int i,t=1,T;
		BigInteger a,b;
		Scanner scan = new Scanner(System.in);
		T=scan.nextInt();
		while(T-->0) {
			a = scan.nextBigInteger();
			b = scan.nextBigInteger();
			System.out.println("Case #"+ t++ +":\n"+a.subtract(b));
		}
	}

}