#include<iostream>

#include<cstdio>

#include<cstring>

using namespace std;

const int MAXN = ;

inline int rd(){

    int x=,f=;char ch=getchar();

    while(!isdigit(ch)) {f=ch=='-'?:;ch=getchar();}

    while(isdigit(ch))  {x=(x<<)+(x<<)+ch-'';ch=getchar();}

    return f?x:-x;

}

int n,r,a[MAXN][MAXN],ans;

int main(){

    n=rd(),r=rd();int x,y,w;

    for(int i=;i<=n;i++){

        x=rd(),y=rd(),w=rd();x++;y++;

        a[x][y]=w;

    }

    for(int i=;i<=;i++)

        for(register int j=;j<=;j++)

            a[i][j]=a[i][j]+a[i-][j]+a[i][j-]-a[i-][j-];

    for(register int i=r;i<=;i++)

        for(register int j=r;j<=;j++)

            ans=max(ans,a[i][j]-a[i-r][j]-a[i][j-r]+a[i-r][j-r]);

    cout<<ans<<endl;

    return ;

}