import sys
from collections import deque
from itertools import combinations
n, m = map(int, sys.stdin.readline().split())
board = [list(map(int, sys.stdin.readline().split())) for _ in range(n)]
directions = ((-1, 0), (0, 1), (1, 0), (0, -1))
# get list of viruses
virus_list = deque()
empty_rooms = 0
for i in range(n):
for j in range(n):
if board[i][j] == 0:
empty_rooms += 1
elif board[i][j] == 2:
virus_list.appendleft((i, j))
answer = sys.maxsize - 1
# for all combinations of viruses
for selected in combinations(virus_list, m):
q = deque()
visited = set()
for virus in selected:
q.appendleft((virus, 0))
visited.add(virus)
# bfs
infected, max_dist = 0, 0
while q:
cur, dist = q.pop()
for dr, dc in directions:
next_r = cur[0] + dr
next_c = cur[1] + dc
if -1 < next_r < n and -1 < next_c < n:
if (next_r, next_c) not in visited:
if board[next_r][next_c] != 1:
# update distance and infection count only if virus is spread in empty room
if board[next_r][next_c] == 0:
infected += 1
max_dist = max(max_dist, dist + 1)
q.appendleft(((next_r, next_c), dist + 1))
visited.add((next_r, next_c))
# update answer if we succeeded in spreading virus
if infected == empty_rooms:
answer = min(answer, max_dist)
# if answer is not found
if answer == sys.maxsize - 1:
print(-1)
# if answer is found
else:
print(answer)
