Problems

# Depth 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 data

The first line contains the number of vertices n and the selected vertex s~(1 \le s \le n \le 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 data

Print the desired number of vertices.

## Examples

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