from collections import deque

def bfs():
    q = deque([])
    dist1 = [[10**18]*W for _ in range(H)] #↓↑
    dist2 = [[10**18]*W for _ in range(H)] #↑↓
    
    if M[0][0]>M[0][1]:
        q.append((0, 1, -1, M[0][0]))
        dist2[0][1] = 1
    elif M[0][0]<M[0][1]:
        q.append((0, 1, 1, M[0][0]))
        dist1[0][1] = 1
    
    if M[0][0]>M[1][0]:
        q.append((1, 0, -1, M[0][0]))
        dist2[1][0] = 1
    elif M[0][0]<M[1][0]:
        q.append((1, 0, 1, M[0][0]))
        dist1[1][0] = 1
    
    while q:
        cx, cy, flag, prev_prev = q.popleft()
        
        if flag==-1:
            for nx, ny in [(cx-1, cy), (cx+1, cy), (cx, cy-1), (cx, cy+1)]:
                if 0<=nx<H and 0<=ny<W and dist1[nx][ny]==10**18 and M[cx][cy]<M[nx][ny] and M[nx][ny]!=prev_prev:
                    dist1[nx][ny] = dist2[cx][cy]+1
                    q.append((nx, ny, 1, M[cx][cy]))
        else:
            for nx, ny in [(cx-1, cy), (cx+1, cy), (cx, cy-1), (cx, cy+1)]:
                if 0<=nx<H and 0<=ny<W and dist2[nx][ny]==10**18 and M[cx][cy]>M[nx][ny] and M[nx][ny]!=prev_prev:
                    dist2[nx][ny] = dist1[cx][cy]+1
                    q.append((nx, ny, -1, M[cx][cy]))
    
    return min(dist1[-1][-1], dist2[-1][-1])
    
W, H = map(int, input().split())
M = [list(map(int, input().split())) for _ in range(H)]
ans = bfs()

if ans==10**18:
    print(-1)
else:
    print(ans)