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)) < len(A): 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)]
que = deque([[1,0,M[0][0],1], [0,1,M[0][0],1]])
cost = [[[[-1]*W for i in xrange(H)] for j in xrange(10)] for k in xrange(10)]
cost[0][M[0][0]][1][0] = cost[0][M[0][0]][0][1] = 1

while que:
    w,h,b,d = que.popleft()
    if (w,h) == (W-1,H-1):
        print d
        break
    cost[b][M[h][w]][h][w] = d
    for dx,dy in dxy:
        nw,nh = w+dx,h+dy
        if not (0 <= nw < W and 0 <= nh < H): continue
        if not isKadomatsu(b, M[h][w], M[nh][nw]): continue
        if cost[M[h][w]][M[nh][nw]][nh][nw] != -1: continue
        que.append([nw,nh,M[h][w],d+1])
else:
    print -1