#include<iostream>
#include<cstring>
#include<algorithm>

using namespace std;

const int N=5010;

int s[N][N];
int main()
{
    int n,m;
    cin>>n>>m;

    m=min(m,5001);

    for (int i = 0; i < n; i++) {
        int x, y, w;
        cin >> x >> y >> w;
        s[++x][++y] += w; 
    }



    for(int i=1; i<=5001; i++)
        for(int j=1; j<=5001; j++)
            s[i][j]+=s[i-1][j]+s[i][j-1]-s[i-1][j-1];


    int res=0;        

    for(int i=m;i<=5001;i++)
        for(int j=m;j<=5001;j++)
            res=max(res,s[i][j]-s[i-m][j]-s[i][j-m]+s[i-m][j-m]);



    cout<<res<<endl;
    return 0;

}