h,w = map(int,input().split())
a = [list(map(int,input().split())) for _ in range(h)]
vij = []
for i in range(h):
    for j in range(w):
        vij.append((a[i][j],i,j))
dp = [[1]*w for _ in range(h)]
for v,pi,pj in sorted(vij):
    for di,dj in ((-1,0),(1,0),(0,-1),(0,1)):
        ni,nj = pi+di,pj+dj
        if h>ni>=0<=nj<w and a[ni][nj]>v:
            dp[ni][nj] = max(dp[ni][nj],dp[pi][pj]+1)
print(max(max(dp[i]) for i in range(h)))