Even Pair Sum December Long challenge problem solution

 Problem Statement-

This problem Even Pair sum is taken from December long challenge 2020. let's read the problem statement.

You are given two positive integers A$A$ and B$B$. Find the number of pairs of positive integers (X,Y)$(X,Y)$ such that 1≤X≤A$1\le X\le A$, 1≤Y≤B$1\le Y\le B$ and X+Y$X+Y$ is even.

Input

• The first line of the input contains a single integer T$T$ denoting the number of test cases. The description of T$T$ test cases follows.
• The first and only line of each test case contains two space-separated integers A$A$ and B$B$.

Output

For each test case, print a single line containing one integer ― the number of valid pairs.

Constraints

• 1≤T≤1,000$1\le T\le 1,000$
• 1≤A,B≤109$1\le A,B\le {10}^9$

Subtasks

Subtask #1 (10 points): A,B≤10$A,B\le 10$

Subtask #2 (10 points): A,B≤1,000$A,B\le 1,000$

Subtask #3 (80 points): original constraints

Example Input

4
1 1
2 3
4 6
8 9

Example Output

1
3
12
36

Solution-

Hint- There is Very big role of even odd in this problem.

In this problem we have to calculate even and odd numbers till A and B.

because odd+odd=even

even +even =even

Here is my solution 

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