B"A batch of n goods ( n -- an even number) is brought to the store, i -th of which has weight a_i . Before selling the goods, they must be packed into packages. After packing, the following will be done: With this, the cost of a package of weight x is always <= ft lfloor frac{x}{k} right rfloor burles (rounded down), where k -- a fixed and given value. Pack the goods to the packages so that the revenue from their sale is maximized. In other words, make such frac{n}{2} pairs of given goods that the sum of the values <= ft lfloor frac{x_i}{k} right rfloor , where x_i is the weight of the package number i ( 1 <= i <= frac{n}{2} ), is maximal. For example, let n = 6, k = 3 , weights of goods a = [3, 2, 7, 1, 4, 8] . Let's pack them into the following packages. With this packing, the total cost of all packs would be 5 + 2 + 1 = 8 burles. The first line of the input contains an integer t ( 1 <= t <= 10^4 ) --the number of test cases in the test. The descriptions of the test cases follow. The first line of each test case contains two integers n ( 2 <= n <= 2 cdot10^5 ) and k ( 1 <= k <= 1000 ). The number n -- is even. The second line of each test case contains exactly n integers a_1, a_2, ... , a_n ( 0 <= a_i <= 10^9 ). It is guaranteed that the sum of n over all the test cases does not exceed 2 cdot10^5 . For each test case, print on a separate line a single number -- the maximum possible total cost of all the packages. The first test case is analyzed in the statement. In the second test case, you can get a total value equal to 4 if you put the first and second goods in the first package and the third and fourth goods in the second package. In the third test case, the cost of each item is 0 , so the total cost will also be 0 . "...