B'You are given a graph consisting of n vertices and m directed arcs. The i -th arc goes from the vertex x_i to the vertex y_i , has capacity c_i and weight w_i . No arc goes into the vertex 1 , and no arc goes from the vertex n . There are no cycles of negative weight in the graph (it is impossible to travel from any vertex to itself in such a way that the total weight of all arcs you go through is negative). You have to assign each arc a flow (an integer between 0 and its capacity, inclusive). For every vertex except 1 and n , the total flow on the arcs going to this vertex must be equal to the total flow on the arcs going from that vertex. Let the flow on the i -th arc be f_i , then the cost of the flow is equal to sum limits_{i = 1}^{m} f_i w_i . You have to find a flow which minimizes the cost. Sounds classical, right? Well, we have some additional constraints on the flow on every edge: Can you solve this problem? The first line contains two integers n and m ( 2 <= n <= 100 ; 1 <= m <= 200 ). Then m lines follow. The i -th of them contains four integers x_i , y_i , c_i , and w_i ( 1 <= x_i <= n - 1 ; 2 <= y_i <= n ; x_i ne y_i ; 1 <= c_i <= 100 ; -100 <= w_i <= 100 ). These integers describe the i -th arc. Additional constraints on the input: If a flow satisfying all of the constraints does not exist, print Impossible. Otherwise, print two lines: If there are multiple answers, print any of them. Note that the cost of the flow should be minimized. '...