from heapq import heappop,heappush
I=lambda:map(int,raw_input().split());W,H=I();G=(W-1,H-1)
M=[I()for i in range(H)];dxy=((1,0),(0,1),(-1,0),(0,-1))
C=[[[W*H+1]*10 for i in range(W)]for i in range(H)];Q=[]
for x,y in dxy[:2]:C[y][x][M[0][0]]=1;Q+=[(1,(x,y),M[0][0])]
while Q:
	c,h,b=heappop(Q)
	if h==G:print c;break
	t=M[h[1]][h[0]];nc=c+1
	for dx,dy in dxy:
		nx=h[0]+dx;ny=h[1]+dy
		if 0<=nx<W and 0<=ny<H:
			n=M[ny][nx]
			if(n-t)*(t-b)<0 and b!=n and nc<C[ny][nx][t]:
				heappush(Q,(nc,(nx,ny),t));C[ny][nx][t]=nc
else:
	print -1