Given an undirected graph. Find the shortest distance between two specified vertices. \InputFile The first line contains three positive integers $n, s$ and $f\:(1 \le s, f \le n \le 100)$ --- the number of vertices in the graph and the numbers of the initial and final vertices. Then, in $n$ lines, the adjacency matrix of the graph is given. If the value in the $j$-th element of the $i$-th row is $1$, then there is a directed edge from vertex $i$ to vertex $j$ in the graph. \OutputFile Print the minimum distance from the initial vertex to the final one. If the path does not exist, then print $0$. \includegraphics{https://static.e-olymp.com/content/37/37e209e3bcdf6dd58dcff5aa802392972e835fd4.gif}