Fill the Bucket

 Chef has a bucket having a capacity of 

K$K$ liters. It is already filled with X$X$ liters of water.

Find the maximum amount of extra water in liters that Chef can fill in the bucket without overflowing.

Input Format

• The first line will contain T$T$ - the number of test cases. Then the test cases follow.
• The first and only line of each test case contains two space separated integers K$K$ and X$X$ - as mentioned in the problem.

Output Format

For each test case, output in a single line, the amount of extra water in liters that Chef can fill in the bucket without overflowing.

Constraints

• 1≤T≤100$1\le T\le 100$
• 1≤X<K≤1000$1\le X<K\le 1000$

Sample Input 1 

2
5 4
15 6

Sample Output 1 

1
9

Explanation

Test Case 1$1$: The capacity of the bucket is 5$5$ liters but it is already filled with 4$4$ liters of water. Adding 1$1$ more liter of water to the bucket fills it to (4+1)=5$(4+1)=5$ liters. If we try to fill more water, it will overflow.

Test Case 2$2$: The capacity of the bucket is 15$15$ liters but it is already filled with 6$6$ liters of water. Adding 9$9$ more liters of water to the bucket fills it to (6+9)=15$(6+9)=15$ liters. If we try to fill more water, it will overflow.