public class Main {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        int m = s.nextInt();
        for (int i = 0 ; i < m ; i ++){
            long n = s.nextLong() , k = s.nextLong();
            if(k == 2) System.out.println(1);
            else if(k == 4){
                long p = 1;
                if(n >= 2) p += n - 2 + 1;
                if(n >= 3) p += n - 3;
                System.out.println(p);
            }else if(k >= 5){
                long p = 1;
                if(n >= 2) p += n - 2 + 1 + 1;
                if(n >= 3) p += n - 3 + 1;
                System.out.println(p);
            }else System.out.println(0);
        }
    }
}