import java.math.BigInteger;
import java.util.Scanner;

public class Main {

    public static void main(String [] args)
    {
        int test,i;
        BigInteger a,b,result;

        Scanner sc = new Scanner(System.in);
        test = sc.nextInt();

        for(i=1; i<=test ;i++)
        {
            a=sc.nextBigInteger();
            b=sc.nextBigInteger();

            result = b.remainder(a);

            System.out.println(""+result);
        }

    }
}