Competitions

# Depth First Search

# Depth Search

The undirected unweighted graph with one selected vertex is given. Find the number of vertices in the connected component where the selected vertex (including the selected vertex).

#### Input

The first line contains the number of vertices **n** and the selected vertex **s** (**1** ≤ **s** ≤ **n** ≤ **100**). In the next **n** lines given **n** integers - the adjacency matrix of a graph, where "**0**" means the absence of an edge, and "**1**" means the presence of an edge. It is guaranteed that the main diagonal of the matrix contains zeros.

#### Output

Print the desired number of vertices.

Input example #1

5 1 0 1 1 0 0 1 0 1 0 0 1 1 0 0 0 0 0 0 0 1 0 0 0 1 0

Output example #1

3

Input example #5

10 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Output example #5

2