H,W=map(int,input().split())
A=[]
for _ in range(H):
    A.append(list(map(int,input().split())))
lis=[]
for i in range(H):
    for j in range(W):
        lis.append((A[i][j],i,j))
lis.sort(reverse=True)
d=[[1,0],[-1,0],[0,1],[0,-1]]
dp=[[1]*W for _ in range(H)]
for a,i,j in lis:
    for dx,dy in d:
        if 0<=i+dx<H and 0<=j+dy<W and A[i+dx][j+dy]>A[i][j]:
            dp[i][j]=max(dp[i+dx][j+dy]+1,dp[i][j])
ans=0
for i in range(H):
    ans=max(max(dp[i]),ans)
print(ans)