from functools import lru_cache
from sys import setrecursionlimit
setrecursionlimit(10**5)

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

@lru_cache(maxsize=None)
def dfs(i, j):
    # 4方向全てを見て、大きいものがなければ1を返す
    res = 1
    for dx, dy in ((1, 0), (0, 1), (-1, 0), (0, -1)):
        ni, nj = i + dx, j + dy
        if 0 <= ni < H and 0 <= nj < W and A[ni][nj] > A[i][j]:
            res = max(res, dfs(ni, nj) + 1)

    return res

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

print(ans)