A. The Miracle and the Sleepertime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputYou 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.InputEach 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).OutputFor 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.ExampleInput
4
1 1
999999999 1000000000
8 26
1 999999999
Output
0
1
12
499999999
NoteIn 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.
4
1 1
999999999 1000000000
8 26
1 999999999

0 1 12 499999999 
['greedy', 'math', '*800']