import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes")
no = lambda :print("no");No = lambda :print("No")
#######################################################################
h,w = na()
a = [na() for i in range(h)]

f = []
for i in range(h):
    for j in range(w):
        f.append((a[i][j],i,j))
f = sorted(f)
dp = [[0]*w for i in range(h)]

for x, i, j in f:
    for dx, dy in [(0,1),(1,0),(-1,0),(0,-1)]:
        ni,nj = i+dx,j+dy
        if 0<=ni<h and 0<=nj<w and a[i][j]>a[ni][nj]:
            dp[i][j] = max(dp[i][j],dp[ni][nj]+1)

print(max([max(i) for i in dp])+1)