You want to reach a destination but you decide that you can make moves in two directions only. If you are at position $(x,\ y)$, then you can move to $(x+1,\ y+1)$ or $(x+1,\ y)$. You must start your journey from $(0,\ 0)$ and your destination is $(X,\ Y)$. Your task is to find the minimum number of moves that you require to reach the destination or if he cannot reach the destination.

Input format

• The first line contains an integer $T$ denoting the number of test cases.
• For each test case, there is a single line consisting of two integers $X$ and $Y$.

Output format

For each test case, print a single line denoting the minimum number of moves that you must take to reach the destination. Print -1 if you cannot reach the destination.

Constraints

$1\leq T \leq 1000$

$|X|,|Y|\leq1e9$