CF1562A.The Miracle and the Sleeper

You are given two integers $l$ and $r$ , $l\le r$ . Find the largest possible value of $a \bmod b$ over all pairs $(a, b)$ of integers for which $r\ge a \ge b \ge l$ .

As a reminder, $a \bmod b$ is a remainder we get when dividing $a$ by $b$ . For example, $26 \bmod 8 = 2$ .

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 $l$ , $r$ ( $1\le l \le r \le 10^9$ ).

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

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 $a \bmod b = 1$ .