#include <bits/stdc++.h>
using namespace std;
struct node{
	int high;
	int x;
	int y;
};
bool cmp(node a,node b){
	return a.high>b.high;
}
int maxn,r,c,a[110][110],dp[110][110],use1[4]={0,0,-1,1},use2[4]={1,-1,0,0};
node q[110*110];
int main(){
	scanf("%d %d",&r,&c);
	for(int i=1;i<=r;i++){
		for(int j=1;j<=c;j++){
			dp[i][j]=1;
			scanf("%d",&a[i][j]);
			q[j+(i-1)*r].high=a[i][j];
			q[j+(i-1)*r].x=i;
			q[j+(i-1)*r].y=j;
		}
	}
	sort(q+1,q+1+(r*c),cmp);
	for(int i=1;i<=r*c;i++){
		int zx=q[i].x,zy=q[i].y,h=q[i].high;
		for(int j=0;j<4;j++){
			int hx=zx+use1[j],hy=zy+use2[j];
			if(hx>=1 && hx<=r && hy>=1 && hy<=c && a[hx][hy]>h){
				dp[zx][zy]=max(dp[zx][zy],dp[hx][hy]+1);
			}
		}
		maxn=max(maxn,dp[zx][zy]);
	}
	cout << maxn;
	return 0;
}