The Miracle and the Sleeper

Description:

Input:

Each test contains multiple test cases.

The first line contains one positive integer $$$t$$$ $$$(1\le t\le 10^4)$$$, denoting the number of test cases. Description of the test cases follows.

The only line of each test case contains two integers $$$l$$$, $$$r$$$ ($$$1\le l \le r \le 10^9$$$).

Output:

For every test case, output the largest possible value of $$$a \bmod b$$$ over all pairs $$$(a, b)$$$ of integers for which $$$r\ge a \ge b \ge l$$$.

Sample Input:

4
1 1
999999999 1000000000
8 26
1 999999999

Sample Output:

0
1
12
499999999

Note:

In the first test case, the only allowed pair is $$$(a, b) = (1, 1)$$$, for which $$$a \bmod b = 1 \bmod 1 = 0$$$.

In the second test case, the optimal choice is pair $$$(a, b) = (1000000000, 999999999)$$$, for which $$$a \bmod b = 1$$$.