#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int maxn=510;
int G[maxn][maxn]={0},f[maxn][maxn]={0},mmm=0,n,m;
inline int QR(){
	char ch;
	while(ch=getchar(),ch<'0'||ch>'9');
	int x=ch-48;
	while(ch=getchar(),ch>='0'&&ch<='9')x=x*10+ch-48;
	return x;
}
int sou(int h,int z){
	if(f[h][z]!=1)return f[h][z];
	if(G[h][z]>G[h][z-1])f[h][z]=max(f[h][z],sou(h,z-1)+1);
	if(G[h][z]>G[h-1][z])f[h][z]=max(f[h][z],sou(h-1,z)+1);
	if(G[h][z]>G[h+1][z])f[h][z]=max(f[h][z],sou(h+1,z)+1);
	if(G[h][z]>G[h][z+1])f[h][z]=max(f[h][z],sou(h,z+1)+1);
	mmm=max(mmm,f[h][z]);
	return f[h][z];
}
int main(){
    freopen("shunzhi.in","r",stdin);
    freopen("shunzhi.out","w",stdout);
	n=QR();
	m=QR();
	memset(G,0x7f,sizeof(G));
	for(int i=1;i<=n;i++)for(int j=1;j<=m;j++)f[i][j]=1;
	for(int i=1;i<=n;i++)for(int j=1;j<=m;j++)G[i][j]=QR();
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)sou(i,j);
	printf("%d\n",mmm);
	return 0;
}