The directed weighted graph is given. Find the shortest path from the vertex s to the vertex f.

Input

The first line contains three numbers n, s and f (1 ≤ n ≤ 100, 1 ≤ s, f ≤ n), where n is the number of vertices in a graph. Each of the next n lines contains n numbers - the adjacency matrix of the graph, where the number in the i-th line and j-th column corresponds to the edge from i to j: -1 means the absence of the edge between the vertices, and any non-negative number - the presence of the edge of a given weight. The main diagonal of the matrix contains always zeroes.

Output

Print the required distance or -1 if the path between the given vertices does not exist.