#include<iostream>
#include<cstdio>
using namespace std;
int read()
{
	int x,f=1;
	char ch;
	while(ch=getchar(),!isdigit(ch))if(ch=='-')f=-1;
	x=ch-48;
	while(ch=getchar(),isdigit(ch))x=x*10+ch-48;
	return x*f;
}
void write(int x)
{
	if(x<0)putchar('-'),x=-x;
	int cnt=0;char ch[50];
	while(ch[++cnt]=x%10+48,x/=10);
	while(putchar(ch[cnt]),--cnt);
	putchar('\n');
}
int a[600][600],f[600][600],n,m;
int work(int x,int y)
{
	if(f[x][y]>1)return f[x][y];
	if(a[x+1][y]<a[x][y]&&x+1<=n)f[x][y]=max(f[x][y],work(x+1,y)+1);
	if(a[x][y+1]<a[x][y]&&y+1<=m)f[x][y]=max(f[x][y],work(x,y+1)+1);
	if(a[x-1][y]<a[x][y]&&x-1>0)f[x][y]=max(f[x][y],work(x-1,y)+1);
	if(a[x][y-1]<a[x][y]&&y-1>0)f[x][y]=max(f[x][y],work(x,y-1)+1);
	return f[x][y];
}
int main()
{
	freopen("shunzhi.in","r",stdin);
	freopen("shunzhi.out","w",stdout);
	n=read(),m=read();
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
			a[i][j]=read()+1,f[i][j]=1;
	int ans=0;
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
			ans=max(ans,work(i,j));
	write(ans);
//	system("pause");
}