import io
import sys
from collections import defaultdict, deque, Counter
from itertools import permutations, combinations, accumulate
from heapq import heappush, heappop
from bisect import bisect_right, bisect_left
from math import gcd
import math

_INPUT = """\
6
2 3
1 2 4
3 3 4
2 2
1 1
1 1
4 4
3 1 4 1
5 9 2 6
5 3 5 8
9 7 9 3
"""

def input():
  return sys.stdin.readline()[:-1]

def solve(test):
  H,W=map(int, input().split())
  A=[list(map(int, input().split())) for _ in range(H)]
  order=sorted([(A[i][j],i,j) for i in range(H) for j in range(W)])
  ans=[0]*H*W
  for k in range(H*W):
    h,w=order[k][1],order[k][2]
    for i,j in [(h-1,w),(h+1,w),(h,w-1),(h,w+1)]:
      if 0<=i<H and 0<=j<W and A[i][j]>A[h][w]:
        ans[i*W+j]=max(ans[i*W+j],ans[h*W+w]+1)
  print(max(ans)+1)

def random_input():
  from random import randint,shuffle
  N=randint(1,10)
  M=randint(1,N)
  A=list(range(1,M+1))+[randint(1,M) for _ in range(N-M)]
  shuffle(A)
  return (" ".join(map(str, [N,M]))+"\n"+" ".join(map(str, A))+"\n")*3

def simple_solve():
  return []

def main(test):
  if test==0:
    solve(0)
  elif test==1:
    sys.stdin = io.StringIO(_INPUT)
    case_no=int(input())
    for _ in range(case_no):
      solve(0)
  else:
    for i in range(1000):
      sys.stdin = io.StringIO(random_input())
      x=solve(1)
      y=simple_solve()
      if x!=y:
        print(i,x,y)
        print(*[line for line in sys.stdin],sep='')
        break

#0:提出用、1:与えられたテスト用、2:ストレステスト用
main(0)