//
//  main.cpp
//  P2280 [HNOI2003]激光炸弹
//
//  Created by  Baiwhiter on 2020/10/3.
//

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<cstring>
using namespace std;
const int N=5010;
int g[N][N];
int s[N][N];
int n,m;
int nx,ny;
int ans=0;
void qz(){
    for(int i=1;i<=nx;i++){
        for(int j=1;j<=ny;j++){
            s[i][j]=s[i-1][j]+s[i][j-1]-s[i-1][j-1]+g[i][j];
        }
    }
}
int main(){
    cin>>n>>m;
    nx=ny=m;
    memset(g,0,sizeof(g));
    for(int i=1;i<=n;i++){
        int x,y,z;
        cin>>x>>y>>z;
        nx=max(nx,x+1);
        ny=max(ny,y+1);
        g[x+1][y+1]=z;
    }
    qz();
    for(int i=m;i<=nx;i++){
        for(int j=m;j<=ny;j++){
                ans=max(ans,s[i][j]-s[i-m][j]-s[i][j-m]+s[i-m][j-m]);
            
        }
    }
    
    cout<<ans<<endl;
    return 0;
}