import collections
H, W = map(int, input().split())
H -= 2
A = [list(map(int, input().split())) + [-1] for _ in range(H)] + [[-1] * (W + 1)]
INF = 10 ** 18
dp = [[INF] * (W + 1) for _ in range(H)] + [[INF] * (W + 1)]
que = collections.deque()
for i in range(H):
    if A[i][0] == -1:
        continue
    dp[i][0] = A[i][0]
    que.append((i, 0))
while que:
    X, Y = que.popleft()
    for i in range(-1, 2):
        for j in range(-1, 2):
            SX = X + i
            SY = Y + j
            if A[SX][SY] != -1 and dp[SX][SY] > dp[X][Y] + A[SX][SY]:
                dp[SX][SY] = dp[X][Y] + A[SX][SY]
                que.append((SX, SY))
print(min(v[-2] for v in dp) if min(v[-2] for v in dp) < INF else -1)