from functools import lru_cache

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

@lru_cache(maxsize=None)
def dp(i, j):
    # (i, j)からスタートして何マス歩けるか
    res = 1
    for dx, dy in [(1, 0), (-1, 0), (0, 1), (0, -1)]:
        ni, nj = i+dx, j+dy
        if not (0 <= ni < H and 0 <= nj < W):
            continue
        if A[i][j] < A[ni][nj]:
            res = max(res, dp(ni, nj)+1)
    return res

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

print(ans)