B'You are given an undirected connected graph on n vertices. Each edge of this graph has a weight; the weight of the edge connecting vertices i and j is w_{i,j} (or w_{i,j} = 0 if there is no edge between i and j ). All weights are positive integers. You are also given a positive integer c . You have to build a spanning tree of this graph; i. xe2 x80 x89e. choose exactly (n-1) edges of this graph in such a way that every vertex can be reached from every other vertex by traversing some of the chosen edges. The cost of the spanning tree is the sum of two values: Find any spanning tree with the minimum cost. Since the graph is connected, there exists at least one spanning tree. The first line contains two integers n and c ( 2 <= n <= 20 ; 1 <= c <= 10^6 ). Then n lines follow. The i -th of them contains n integers w_{i,1}, w_{i,2}, ... , w_{i,n} ( 0 <= w_{i,j} <= 10^6 ), where w_{i,j} denotes the weight of the edge between i and j (or w_{i,j} = 0 if there is no such edge). Additional constraints on the input: Print one integer -- the minimum cost of a spanning tree of the given graph. In the first example, the minimum cost spanning tree consists of edges (1, 3) , (2, 3) and (3, 4) . The maximum matching for it is 1 . In the second example, the minimum cost spanning tree consists of edges (1, 2) , (2, 3) and (3, 4) . The maximum matching for it is 2 . '...