from functools import lru_cache

# from sys import setrecursionlimit
# import pypyjit
# setrecursionlimit(10 ** 7)
# pypyjit.set_param('max_unroll_recursion=-1')

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

@lru_cache(maxsize=None)
def dp(x):
    # (i, j)からスタートして何マス歩けるか
    i, j = divmod(x, W)
    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*W+j] < A[ni*W+nj]:
            res = max(res, dp(ni*W+nj)+1)
    return res

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

print(ans)