import Queue
W,H=map(int,raw_input().split())
M= [map(int,raw_input().split()) for i in range(H)]
record=[[[-1 for i in range(10)] for j in range(W)] for k in range(H)]
for i in range(10):
    record[0][0][i]=0
q=Queue.Queue()
record[1][0][M[0][0]]=1
q.put((1,0,M[0][0]))
record[0][1][M[0][0]]=1
q.put((0,1,M[0][0]))
d=[(1,0),(-1,0),(0,1),(0,-1)]
while not q.empty():
    i,j,prev=q.get()
    #print i,j,prev,record[i][j][prev]
    for dx,dy in d:
        if i+dx>=0 and i+dx <H and j+dy >= 0 and j+dy<W:
            if record[i+dx][j+dy][M[i][j]]==-1:
                if M[i+dx][j+dy]!=M[i][j] and M[i+dx][j+dy]!=prev:
                    if (M[i][j]-prev)*(M[i][j]-M[i+dx][j+dy]) > 0:
                        record[i+dx][j+dy][M[i][j]]=record[i][j][prev]+1
                        q.put((i+dx,j+dy,M[i][j]))
                        if i+dx+1==H and j+dy+1==W:
                            print record[i+dx][j+dy][M[i][j]]
                            exit()
print -1