#include<bits/stdc++.h>
using namespace std;
const int N=1e2+9;
long long r,c,a[N][N],f[N][N],ans;
long long w[5]={0,0,1,-1};
long long s[5]={1,-1,0,0};
priority_queue <pair<long long,pair<long long ,long long>>> q;
int main(){
	scanf("%lld%lld",&r,&c);
	for(int i=1;i<=r;i++)for(int j=1;j<=r;j++){
		scanf("%lld",&a[i][j]);	
		q.push({a[i][j],{i,j}});
	}
	while(!q.empty()){
		auto k=q.top();q.pop();
		f[k.second.first][k.second.second]++;
		for(int i=0;i<4;i++)if(k.first>a[k.second.first+w[i]][k.second.second+s[i]])f[k.second.first+w[i]][k.second.second+s[i]]=max(f[k.second.first+w[i]][k.second.second+s[i]],f[k.second.first][k.second.second]);
		ans=max(f[k.second.first][k.second.second],ans);
	}
	printf("%lld",ans);
	return 0;
}