B'You are given a set of n elements indexed from 1 to n. The weight of i-th element is wi. The weight of some subset of a given set is denoted as . The weight of some partition R of a given set into k subsets is (recall that a partition of a given set is a set of its subsets such that every element of the given set belongs to exactly one subset in partition). Calculate the sum of weights of all partitions of a given set into exactly k non-empty subsets, and print it modulo 109 xe2 x80 x89+ xe2 x80 x897. Two partitions are considered different iff there exist two elements x and y such that they belong to the same set in one of the partitions, and to different sets in another partition. The first line contains two integers n and k (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89k xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89n xe2 x80 x89 xe2 x89 xa4 xe2 x80 x892 xc2 xb7105) -- the number of elements and the number of subsets in each partition, respectively. The second line contains n integers wi (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89wi xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89109) -- weights of elements of the set. Print one integer -- the sum of weights of all partitions of a given set into k non-empty subsets, taken modulo 109 xe2 x80 x89+ xe2 x80 x897. Possible partitions in the first sample: Possible partitions in the second sample: '...