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


H, W = map(int, input().split())
A = []
for _ in range(H):
    A.append(list(map(int, input().split())))

xs = []
for i in range(H):
    for j in range(W):
        xs.append((A[i][j], i, j))

dp = [[1] * W for _ in range(H)]
for _, r, c in sorted(xs, key=lambda x: x[0]):
    for nr, nc in neighbors4(r, c):
        if A[nr][nc] > A[r][c]:
            dp[nr][nc] = max(dp[nr][nc], dp[r][c] + 1)

ans = 0
for i in range(H):
    for j in range(W):
        ans = max(ans, dp[i][j])

print(ans)