donation drive

Problem
A blood drive aims to collect N number of blood donations.
The drive has collected X donations so far. Find the remaining number of donations needed to reach the target.

Input Format
The first line of input will contain a single integer T, denoting the number of test cases.
Each test case contains two space-separated integers N and X — the number of required donations and the number of collected donations, respectively.

/* package codechef; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Codechef
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner sc=new Scanner(System.in);
		int t=sc.nextInt();
		for(int i=0;i<t;i++){
		    int a=sc.nextInt();
		    int b=sc.nextInt();
		    int c=a-b;
		    System.out.println(c);
		}// your code goes here
	}
}