B"Let's consider Euclid's algorithm for finding the greatest common divisor, where t is a list: There is an array p of pairs of positive integers that are not greater than m . Initially, the list t is empty. Then the function is run on each pair in p . After that the list t is shuffled and given to you. You have to find an array p of any size not greater than 2 cdot 10^4 that produces the given list t , or tell that no such array exists. The first line contains two integers n and m ( 1 <= n <= 10^3 , 1 <= m <= 10^9 ) -- the length of the array t and the constraint for integers in pairs. The second line contains n integers t_1, t_2, ldots, t_n ( 1 <= t_i <= m ) -- the elements of the array t . The i -th of the next k lines should contain two integers a_i and b_i ( 1 <= a_i, b_i <= m ) -- the i -th pair in p . If there are multiple valid answers you can output any of them. In the first sample let's consider the array t for each pair: So in total t = [8, 3, 2, 1, 6, 3, 1] , which is the same as the input t (up to a permutation). In the second test case it is impossible to find such array p of pairs that all integers are not greater than 10 and t = [7, 1] In the third test case for the pair (15, , 8) array t will be [7, 1] . "...