import sys
from collections import deque
sys.setrecursionlimit(100000)
dxy = zip([1,0,-1,0],[0,1,0,-1])
def isKadomatsu(*A):
    if len(set(A)) < 3: return False
    med = sorted(A)[1]
    return True if A.index(med) != 1 else False
    
W,H = map(int,raw_input().split())
M = [map(int,raw_input().split()) for i in xrange(H)]
D = [[10**6]*W for i in xrange(H)]
que = deque([[0,0,0,0,0]])
while que:
    w,h,bw,bh,n = que.popleft()
    if (w,h) == (W-1,H-1):
        print n
        break
    for dx,dy in dxy:
        nw,nh = w+dx,h+dy
        if 0 <= nw < W and 0 <= nh < H:
            if D[nh][nw] < D[h][w]+1: continue
            if not isKadomatsu(M[bh][bw],M[h][w],M[nh][nw]): continue
            que.append([nw,nh,w,h,n+1])
else:
    print -1