from collections import deque

def bfs():
    dist = [[[[-1]*2 for _ in range(10)] for _ in range(W)] for _ in range(H)]
    q = deque([])
    
    if M[0][0]!=M[0][1]:
        flag = 1 if M[0][1]>M[0][0] else 0
        dist[0][1][M[0][0]][flag] = 1
        q.append((0, 1, M[0][1], M[0][0]))
    
    if M[0][0]!=M[1][0]:
        flag = 1 if M[1][0]>M[0][0] else 0
        dist[1][0][M[0][0]][flag] = 1
        q.append((1, 0, M[1][0], M[0][0]))
    
    while q:
        cx, cy, cur, prev = q.popleft()
        
        for nx, ny in [(cx-1, cy), (cx+1, cy), (cx, cy-1), (cx, cy+1)]:
            if not (0<=nx<H and 0<=ny<W):
                continue
            
            flag = 1 if M[nx][ny]>cur else 0
            flag2 = 1 if cur>prev else 0

            if M[nx][ny] not in [cur, prev] and flag^flag2==1 and dist[nx][ny][cur][flag]==-1:
                dist[nx][ny][cur][flag] = dist[cx][cy][prev][flag2]+1
                q.append((nx, ny, M[nx][ny], cur))
    
    return dist
            
W, H = map(int, input().split())
M = [list(map(int, input().split())) for _ in range(H)]
dist = bfs()
ans = 10**18

for i in range(10):
    for j in range(2):
        if dist[H-1][W-1][i][j]==-1:
            continue
        
        ans = min(ans, dist[H-1][W-1][i][j])

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