n, s = list(map(int, input().split()))
graph = [[] for i in range(n)]
for i in range(n):
    arr = list(map(int, input().split()))
    for j in range(n):
        if arr[j] == 1:
            graph[i].append(j)

ans = 1
used = [False for i in range(n)]
used[s - 1] = True

def dfs(s):
    global ans, used, graph
    for i in range(len(graph[s])):
        if used[graph[s][i]] == False:
            used[graph[s][i]] = True
            ans += 1
            dfs(graph[s][i])
    return

dfs(s - 1)
print(ans)