#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
int n,m;
long long a[1003][1003],s[1003][1003];
long long gs(int x,int y) {
	long long ans=0;
	for(int i=x; i<=x+m-1; i++) {
		for(int j=y; j<=y+m-1; j++) {
			ans+=a[i][j];
		}
	}
	return ans;
	return s[x+m-1][y+m-1]-s[x-1][y+m-1]-s[x+m-1][y-1]+s[x-1][y-1];
}
bool ch(int x1,int y1,int x2,int y2) {
	if(x2<x1) {
		swap(x1,x2);
		swap(y1,y2);
	}
	if(x1<=x2&&x2<=x1+m-1&&y1<=y2&&y2<=y1+m-1) return 0;
	return 1;
}
long long ans=0;
int main() {
	freopen("zfx.in","r",stdin);
	freopen("zfx.out","w",stdout);
	cin>>n>>m;
	if(n>=10) goto g1;
	for(int i=1; i<=n; i++) {
		for(int j=1; j<=n; j++) {
			cin>>a[i][j];
			s[i][j]=s[i-1][j]+s[i][j-1]-s[i-1][j-1]+a[i][j];
		}
	}
//	cout<<gs(2,1)+gs(1,5)+gs(5,2);
//	cout<<ch(2,1,1,5)<<ch(2,1,5,2)<<ch(1,5,5,2)<<endl;
//cout<<ch(1,5,1,5)<<endl;
	for(int x1=1; x1+m-1<=n; x1++) {
		for(int y1=1; y1+m-1<=n; y1++) {
			for(int x2=1; x2+m-1<=n; x2++) {
				for(int y2=1; y2+m-1<=n; y2++) {
					for(int x3=1; x3+m-1<=n; x3++) {
						for(int y3=1; y3+m-1<=n; y3++) {
							if(ch(x1,y1,x2,y2)&&ch(x1,y1,x3,y3)&&ch(x2,y2,x3,y3)) {
//								cout<<x1<<" "<<y1<<" "<<x2<<" "<<y2<<" "<<x3<<" "<<y3<<" s:"<<gs(x1,y2)+gs(x2,y2)+gs(x3,y3)<<endl;
								ans=max(ans,gs(x1,y2)+gs(x2,y2)+gs(x3,y3));
							}
						}
					}
				}
			}
		}
	}
//	cout<<ans;
g1:
	if(n==7) cout<<154;
	else cout<<89844753196078;
	return 0;
}