from heapq import heappop,heappush
H,W = map(int,input().split())
G = []
color = []

for i in range(H):
    G.append(list(map(int,input().split())))
    color.append([-1]*W)

now1 = (0,0)
now2 = (H-1,W-1)

Q1,Q2 = [],[]
heappush(Q1,(G[0][0],0,0))
heappush(Q2,(G[H-1][W-1],H-1,W-1))

cnt = 0
dir = [(-1,0),(1,0),(0,-1),(0,1)]

while True:
    if cnt % 2 == 0:
        if Q1:
            val,h,w = heappop(Q1)

            if color[h][w] != -1:
                continue

            color[h][w] = 0
            cnt += 1

            for a,b in dir:
                if 0 <= h+a < H and 0 <= w+b < W:
                    if color[h+a][w+b] == 1:
                        print(cnt-2)
                        exit()
                    elif color[h+a][w+b] == -1:
                        heappush(Q1,(G[h+a][w+b],h+a,w+b))
        else:
            print(cnt-2)
            exit()
    else:
        if Q2:
            val,h,w = heappop(Q2)
            if color[h][w] != -1:
                continue
            color[h][w] = 1
            cnt += 1
            for a,b in dir:
                if 0 <= h+a < H and 0 <= w+b < W:
                    if color[h+a][w+b] == 0:
                        print(cnt-2)
                        exit()
                    elif color[h+a][w+b] == -1:
                        heappush(Q2,(G[h+a][w+b],h+a,w+b))
        else:
            print(cnt-2)
            exit()