# 1.输入示例
r,c = map(int, input().split())

arr = [[0 for i in range(c+1)] for j in range(r+1)]
for i in range(1, r+1):
    in_li = list(map(int, input().split()))   
    for j in range(1, c+1):
        arr[i][j] = in_li[j-1]

# 2. 初始化dp数组
dp = [[-1 for i in range(c+1)] for j in range(r+1)]


# 3.递归搜索
dx = [-1,0,1,0]    # ！！！技巧：遍历方格的上下左右四个方向的技巧，新建两个这样的数组
dy = [0,1,0,-1]

def dfs(i,j):
    if  dp[i][j]!=-1:
        return dp[i][j]
    dp[i][j] = 1    # 初始化dp[i][j]等于1，表示路劲只包含[i,j]元素，长度为1
    for d in range(4):
        a = i+dx[d]
        b = j+dy[d]
        if a>=1 and a<=r and b>=1 and b<=c and arr[a][b]<arr[i][j]:    # !出错，最后要比较arr数组中移动一个位置前后的高度大小
            dp[i][j] = max(dp[i][j], dfs(a,b)+1)
    return dp[i][j]

res = 0
for i in range(1, r+1):
    for j in range(1, c+1):
        res = max(res, dfs(i,j))
print(res)