Problem Statement:

The number S is called the mean of two numbers R1 and R2 if S is equal to (R1+R2) / 2. Mirko's birthday present for Slavko was two integers R1 and R2. Slavko promptly calculated their mean which also happened to be an integer but then lost R2! Help Slavko restore R2.

Input Format:

The first line contains T denoting the number of test cases. T blocks follow. For each test case, there is one line containing two integers R1 and S, both between -1000 and 1000.

Output Format:

For each test case, output R2 on a single line.

Sample Input:

2
11 15
4 3

Sample Output:

19
2