Path

Input

The first line of the input contains the integer $N$ – the number of vertices in the graph (1 \leq N \leq 100). Next, the adjacency matrix is given, where $0$ means there is no edge, and $1$ means there is an edge. After that, the numbers of the two vertices are given: the start and the end vertex.

Output

Output $L$ – the length of the shortest path (the number of edges to be traversed). If there is no such path, output $-1$.

Examples