from collections import defaultdict, deque


def neighbors4(r: int, c: int) -> list[tuple[int, int]]:
    res = []
    for dr, dc in [(-1, 0), (1, 0), (0, -1), (0, 1)]:
        nr = r + dr
        nc = c + dc
        if not (0 <= nr < H and 0 <= nc < W): continue
        res.append((nr, nc))

    return res


def is_kadomatu(a, b, c) -> bool:
    if a == c: return False
    if a < b > c: return True
    if a > b < c: return True
    return False


INF = 1 << 62
W, H = map(int, input().split())
G = []
for _ in range(H):
    G.append(list(map(int, input().split())))

used = set()
dists = defaultdict(lambda: INF)
q = deque([
    (1, 1, 0, G[0][0]),
    (1, 0, 1, G[0][0])
    ])

while q:
    step, r, c, x = q.popleft()
    if r == H-1 and c == W-1:
        print(step)
        break

    if (r, c, x) in used: continue
    used.add((r, c, x))

    for nr, nc in neighbors4(r, c):
        if is_kadomatu(G[nr][nc], G[r][c], x):
            q.append((step+1, nr, nc, G[r][c]))
else:
    print(-1)