BOJ_7569.py

# from collections import deque
# import sys
# input = sys.stdin.readline
# q = deque()
#
# n, m, h = map(int, input().split())
# graph = [[list(map(int, sys.stdin.readline().split())) for _ in range(n)] for _ in range(h)]
# dist = [[[0] * n for _ in range(m)] for _ in range(h)]
# isnone = True
#
# for z in range(h):
#     for y in range(m):
#         for x in range(n):
#             if graph[z][y][x] == 1:
#                 q.append((z, y, x))
#                 isnone = False
#
# if isnone:
#     print(-1)
#     sys.exit(0)
#
# dx = [1, -1, 0, 0, 0, 0]
# dy = [0, 0, 1, -1, 0, 0]
# dz = [0, 0, 0, 0, 1, -1]
# while q:
#     a, b, c = q.popleft()
#
#     for i in range(6):
#         x = c + dx[i]
#         y = b + dy[i]
#         z = a + dz[i]
#         if 0 <= x < n and 0 <= y < m and 0 <= z < h:
#             if graph[z][y][x] == 0:
#                 q.append((z, y, x))
#                 graph[z][y][x] = 1
#                 dist[z][y][x] = dist[a][b][c] + 1
#
# day = 0
# for z in range(h):
#     for y in range(m):
#         for x in range(n):
#             if dist[z][y][x] > day:
#                 day = dist[z][y][x]
#
#             elif graph[z][y][x] == 0:
#                 print(-1)
#                 sys.exit(0)
#
# print(day)

from collections import deque
import sys
input = sys.stdin.readline
q = deque()

n, m, h = map(int, input().split())
graph = [[list(map(int, sys.stdin.readline().split())) for _ in range(m)] for _ in range(h)]
dist = [[[0] * n for _ in range(m)] for _ in range(h)]
isnone = True

for z in range(h):
    for y in range(m):
        for x in range(n):
            if graph[z][y][x] == 1:
                q.append((z, y, x))
                isnone = False

if isnone:
    print(-1)
    sys.exit(0)

dx = [1, -1, 0, 0, 0, 0]
dy = [0, 0, 1, -1, 0, 0]
dz = [0, 0, 0, 0, 1, -1]
while q:
    a, b, c = q.popleft()

    for i in range(6):
        x = c + dx[i]
        y = b + dy[i]
        z = a + dz[i]
        if 0 <= x < n and 0 <= y < m and 0 <= z < h:
            if graph[z][y][x] == 0:
                q.append((z, y, x))
                graph[z][y][x] = 1
                dist[z][y][x] = dist[a][b][c] + 1

day = 0
for z in range(h):
    for y in range(m):
        for x in range(n):
            if dist[z][y][x] > day:
                day = dist[z][y][x]

            elif graph[z][y][x] == 0:
                print(-1)
                sys.exit(0)

print(day)