def isKadomatsu(a,b,c):
    if a == 0 or b == 0: return True
    return b < a < c or b < c < a or a < c < b or c < a < b

dxdy=zip([-1,0,1,0],[0,1,0,-1])
W,H=map(int,raw_input().split())
M=[map(int,raw_input().split()) for i in xrange(H)]
que=[[0,0,0]]
cost=[[[-1]*W for _ in xrange(H)] for i in xrange(10)]
cost[0][0][0]=0
while que:
    w,h,bef=que.pop(0)
    if w==W-1 and h==H-1:
        print cost[bef][h][w]
        break
    cur=M[h][w]
    for dx,dy in dxdy:
        nw,nh=w+dx,h+dy
        if not (0<=nw<W and 0<=nh<H):continue
        aft=M[nh][nw]
        if not (isKadomatsu(bef,cur,aft)):continue
        if cost[cur][nh][nw]!=-1:continue
        cost[cur][nh][nw]=cost[bef][h][w]+1
        que.append([nw,nh,cur])
else:
    print -1