Solve the programming task below in a Python markdown code block.
A city has been infected by a contagious virus.

In a survey, it was found that A out of the N people living in the city are currently infected.
It has been observed that the only way for a person to get infected is if he comes in contact with an already infected person, and both of them are NOT wearing a mask.

The mayor of the city wants to make a new Mask Policy and find out the minimum number of people that will be required to wear a mask to avoid the further spread of the virus.
Help the mayor in finding this number.

Note: The only aim of the mayor is to stop virus spread, not to mask every infected person.

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

- The first line contains T - number of test cases. Then the test cases follow.
- The first and only line of each test case contains two integers N and A - the total number of people living in the city and the number of people already affected by the virus respectively.

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

For each test case, output the minimum number of people that will be required to wear a mask so as to curb the virus spread.

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

$1 ≤ T ≤ 10^{5}$
$2 ≤ N ≤ 400$
$1 ≤ A < N$

----- Sample Input 1 ------ 
3
2 1
3 2
3 1
----- Sample Output 1 ------ 
1
1
1
----- explanation 1 ------ 
Test Case #1: There is $1$ infected person and $1$ uninfected person. We can ask any of them to wear a mask, and no more infections will occur. Hence the answer is $1$.

Test Case #2: There are $2$ infected people and $1$ uninfected person. We can ask the uninfected person to wear a mask, and no more infections will occur. Hence the answer is $1$.

Test Case #3: There is $1$ infected person and $2$ uninfected people. We can ask the single infected person to wear a mask, and no more infections will occur. Hence the answer is $1$.