dxdy=zip([-1,0,1,0],[0,1,0,-1])
def kadomatsu(a,b,c):
    if a==0 or b==0:
        return True
    else:
        if (a!=b and b!=c and c!=a) and not (a<b<c or a>b>c):
            return True
        else:
            return False
W,H=map(int,raw_input().split())
M=[map(int,raw_input().split()) for _ 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:
    [bef,x,y]=que.pop(0)
    cur=M[y][x]
    if x==W-1 and y==H-1:
        print cost[bef][y][x]
        exit()
    for dx,dy in dxdy:
        nx,ny=x+dx,y+dy
        if not(0<=nx<W and 0<=ny<H):continue
        aft=M[ny][nx]
        if not kadomatsu(bef,cur,aft):continue
        if cost[cur][ny][nx]!=-1:continue
        cost[cur][ny][nx]=cost[bef][y][x]+1
        que.append([cur,nx,ny])
print -1