import sys
read=sys.stdin.buffer.read
readline=sys.stdin.buffer.readline
readlines=sys.stdin.buffer.readlines

w, h=map(int, readline().split())
m=list(map(int, read().split()))
from collections import deque
que=deque()
INF=10**9
dp=[[INF]*(w*h) for _ in range(4)]
dp[0][0]=0
que.append((0, 0))
dx=[1, -1, 0, 0]
dy=[0, 0, 1, -1]
def is_kadomatsu(a, b, c):
    if a!=c and ((a<b and b>c) or (a>b and b<c)):
        return True
    else:
        return False
while que:
    xy, k=que.popleft()
    x, y=divmod(xy, w)
    d=dp[k][xy]
    x2, y2=x-dx[k], y-dy[k]
    xy2=x2*w+y2
    for i, (a, b) in enumerate(zip(dx, dy)):
        x1, y1=x+a, y+b
        if x1<0 or x1>=h or y1<0 or y1>=w:
            continue
        xy1=x1*w+y1
        if dp[i][xy1]>d+1 and (d==0 or is_kadomatsu(m[xy2], m[xy], m[xy1])):
            dp[i][xy1]=d+1
            que.append((xy1, i))
ans=min(dp[0][-1], dp[2][-1])
if ans==INF:
    print(-1)
else:
    print(ans)