import heapq

D=[[1,0],[0,1],[-1,0],[0,-1]]

H,W=map(int,input().split())
A=[]
for i in range(H):
    A.append([int(_) for _ in input().split()])

C=[[None for j in range(W)] for i in range(H)]

Q=[[(A[H-1][W-1],(H-1,W-1))],[(A[0][0],(0,0))]]
heapq.heapify(Q[1])
heapq.heapify(Q[0])

step = -2
while True:
    step += 1
    k = step%2
    while True:
        _, p = heapq.heappop(Q[k])
        Y, X = p
        if C[Y][X] is None:
            break
    C[Y][X]=k
    f = False
    for d in D:
        y = Y + d[0]
        x = X + d[1]
        if 0<=y<H and 0<=x<W:
            if C[y][x]==1-k:
                f = True
                break
            if C[y][x] is None:
                heapq.heappush(Q[k], (A[y][x],(y,x)))
    if f:
        break
print(step)
'''
for c in C:
    print(*[' ' if _ is None else _ for _ in c])
'''