#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<cstdio>
#define in int
using namespace std;
in n,m,x,ans,y,v,s[5005][5005];
int main(){
	cin>>n>>m;
	for(in i=1;i<=n;i++) cin>>x>>y>>v,s[x][y]=v;
	for(in i=1;i<=5000;i++){
		for(in j=1;j<=5000;j++){
			s[i][j]+=s[i-1][j]+s[i][j-1]-s[i-1][j-1];
		}
	}
	for(in i=m;i<=5000;i++){
		for(in j=m;j<=5000;j++){
			in sum=s[i][j]-s[i-m][j]-s[i][j-m]+s[i-m][j-m];
			if(sum>ans) ans=sum;
		}
	}
	cout<<ans;
	return 0;
}