Solve the programming task below in a Python markdown code block.
In Chefland, everyone who earns strictly more than Y rupees per year, has to pay a tax to Chef. Chef has allowed a special scheme where you can invest any amount of money and claim exemption for it.

You have earned X (X > Y) rupees this year. Find the minimum amount of money you have to invest so that you don't have to pay taxes this year.

------ Input Format ------ 

- The first line of input will contain a single integer T, denoting the number of test cases.
- Each test case consists of a single line of input consisting of two space separated integers X and Y denoting the amount you earned and the amount above which you will have to pay taxes.

------ Output Format ------ 

For each test case, output a single integer, denoting the minimum amount you need to invest.

------ Constraints ------ 

$1 ≤ T ≤ 100$
$1 ≤ Y < X ≤ 100$

----- Sample Input 1 ------ 
4
4 2
8 7
5 1
2 1

----- Sample Output 1 ------ 
2
1
4
1

----- explanation 1 ------ 
Test case $1$: The amount above which you will have to pay taxes is $2$. Since you earn $4$ rupees, you need to invest at least $2$ rupees. After investing $2$ rupees, you will remain with an effective income $4 - 2 = 2$ rupees which will not be taxed.

Test case $2$: The amount above which you will have to pay taxes is $7$. Since you earn $8$ rupees, you need to invest at least $1$ rupees.

Test case $3$: The amount above which you will have to pay taxes is $1$. Since you earn $5$ rupees, you need to invest at least $4$ rupees.

Test case $4$: The amount above which you will have to pay taxes is $1$. Since you earn $2$ rupees, you need to invest at least $1$ rupees.