walk=[
    (1,0),
    (-1,0),
    (0,1),
    (0,-1),
]
from heapq import heapify,heappop,heappush

h,w=map(int,input().split())

a=[list(map(int,input().split())) for i in range(h)]
fi=[[-1]*w for i in range(h)]
fi[0][0]=0
fi[0][1]=2
fi[1][0]=2
fi[-1][-1]=1
fi[-1][-2]=3
fi[-2][-1]=3

que0=[]
que1=[]
heappush(que0,(a[0][1],0,1))
heappush(que0,(a[1][0],1,0))
heappush(que1,(a[h-1][w-2],h-1,w-2))
heappush(que1,(a[h-2][w-1],h-2,w-1))
que=[que0,que1]

def inside(y,x):
    return 0<=y<h and 0<=x<w

for i in range(h*w):
    t_que=que[i%2]
    _,y,x=heappop(t_que)

    fi[y][x]=i%2
    # 隣がo_coloredで塗られている場合exit
    for iy,ix in walk:
        ny,nx=iy+y,ix+x
        if inside(ny,nx) and fi[ny][nx]==(1^(i%2)):
            print(i+1)
            exit()

    for iy,ix in walk:
        ny,nx=iy+y,ix+x
        if inside(ny,nx):
            if fi[ny][nx]==-1 or fi[ny][nx]&1!=i%2:
                if fi[ny][nx]==-1:
                    fi[ny][nx]=2|(i%2)
                else:
                    fi[ny][nx]|=i%2

                heappush(t_que,(a[ny][nx],ny,nx))