import sys, math
sys.setrecursionlimit(10**6)
read=sys.stdin.buffer.read
readline=sys.stdin.readline

from collections import deque
w,h=map(int,readline().split())
ls=[list(map(int,readline().split())) for _ in range(h)]
fin=set()
bfs=deque()
bfs.append([0,0,0,-1])
bfs.append([0,0,0,+10])
while bfs:
  d,i,j,pm=bfs.popleft()
  if (i,j,pm) in fin: continue
  fin.add((i,j,pm))
  m=ls[i][j]
  for di,dj in [(-1,0),(1,0),(0,1),(0,-1)]:
    ni,nj=i+di,j+dj
    if ni<0 or nj<0 or ni==h or nj==w: continue
    nm=ls[ni][nj]
    if nm==m or nm==pm or pm==m or pm<m<nm or pm>m>nm: continue 
    if (ni,nj,m) in fin:continue
    if (ni,nj)==(h-1,w-1): 
      print(d+1)
      print('Took: ' + str(round((time()-t)*1000, 2)) + 'ms', file=sys.stderr)
      exit()
    bfs.append([d+1,ni,nj,m])
print(-1)