#include<bits/stdc++.h>
using namespace std;
const int N=5e3+5;
int  n,m,f[N][N],x,y;
int  ans=-1;
int main()
{
	memset(f,0,sizeof f);
	cin>>n>>m;
	for(int i=1;i<=n;i++)
	{
		int vv;
		cin>>x>>y>>vv;
		f[x++][y++]=vv;
	}	
	for(int i=1;i<N;i++)
	{
		for(int j=1;j<=N;j++)
		{
			f[i][j]=f[i-1][j]+f[i][j-1]-f[i-1][j-1]+f[i][j];
		}
	}		
	for(int i=m;i<N;i++)
	{
		for (int j=m;j<N;j++) 
		{
			int num=f[i][j]-f[i-m][j]-f[i][j-m]+f[i-m][j-m];
			ans=max(ans,num);
    	}		
	}

	cout<<ans;
	return 0;
}