Flip the cards Codechef Solution

Problem

There are $N$ cards on a table, out of which $X$ cards are face-up and the remaining are face-down.

In one operation, we can do the following:

• Select any one card and flip it (i.e. if it was initially face-up, after the operation, it will be face-down and vice versa)

What is the minimum number of operations we must perform so that all the cards face in the same direction (i.e. either all are face-up or all are face-down)?

Input Format

• The first line contains a single integer $T$ — the number of test cases. Then the test cases follow.
• The first and only line of each test case contains two space-separated integers $N$ and $X$ — the total number of cards and the number of cards which are initially face-up.

Output Format

For each test case, output the minimum number of cards you must flip so that all the cards face in the same direction.

Constraints

Sample 1:

4
5 0
4 2
3 3
10 2

0
2
0
2

Explanation:

Test Case 1: All the cards are already facing down. Therefore we do not need to perform any operations.

Test Case 2: $2$ cards are facing up and $2$ cards are facing down. Therefore we can flip the $2$ cards which are initially facing down.

Test Case 3: All the cards are already facing up. Therefore we do not need to perform any operations.

Test Case 4: $2$ cards are facing up and $8$ cards are facing down. Therefore we can flip the $2$ cards which are initially facing up.