B"Let's name a pair of positive integers (x, y) lucky if the greatest common divisor of them is equal to 1 ( gcd(x, y) = 1 ). Let's define a chain induced by (x, y) as a sequence of pairs (x, y) , (x + 1, y + 1) , (x + 2, y + 2) , ... , (x + k, y + k) for some integer k ge 0 . The length of the chain is the number of pairs it consists of, or (k + 1) . Let's name such chain lucky if all pairs in the chain are lucky. You are given n pairs (x_i, y_i) . Calculate for each pair the length of the longest lucky chain induced by this pair. Note that if (x_i, y_i) is not lucky itself, the chain will have the length 0 . The first line contains a single integer n ( 1 <= n <= 10^6 ) -- the number of pairs. Next n lines contains n pairs -- one per line. The i -th line contains two integers x_i and y_i ( 1 <= x_i < y_i <= 10^7 ) -- the corresponding pair. Print n integers, where the i -th integer is the length of the longest lucky chain induced by (x_i, y_i) or -1 if the chain can be infinitely long. In the first test case, gcd(5, 15) = 5 > 1 , so it's already not lucky, so the length of the lucky chain is 0 . In the second test case, gcd(13 + 1, 37 + 1) = gcd(14, 38) = 2 . So, the lucky chain consists of the single pair (13, 37) . "...