from collections import defaultdict as D
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 xrange(H)];dxy=((1,0),(0,1),(-1,0),(0,-1))
C=[[D(lambda:W*H+1)for i in xrange(W)]for i in xrange(H)];Q=[]
for x,y in dxy[:2]:A=(M[0][0],M[y][x]);C[y][x][A]=1;Q+=[(1,(x,y),A)]
while Q:
	c,h,A=heappop(Q)
	if h==G:print c;break
	for dx,dy in dxy:
		nx=h[0]+dx;ny=h[1]+dy
		if 0<=nx<W and 0<=ny<H:
			A2=M[ny][nx];nA=(A[1],A2);nc=c+1
			if(A[0]-A[1])*(A[1]-A2)<0 and A[0]!=A2 and nc<C[ny][nx][A]:
				heappush(Q,(nc,(nx,ny),nA));C[ny][nx][nA]=nc
else:print -1