#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int N=5010;
int s[N][N];
int cnt,r;
int n,m;
int main()
{
cin>>cnt>>r;
r=min(5001,r);
int x,y,val;
n=m=5001;
for(int i=0; i<cnt; i++)
{
cin>>x>>y>>val;
x++,y++;
s[x][y]+=val;
}
n=max(n,x),m=max(m,y);
for(int i=1; i<=n; i++)
for(int j=1; j<=m; j++)
s[i][j]+=s[i-1][j]+s[i][j-1]-s[i-1][j-1];
int res=0;
for(int i=r; i<=n; i++)
for(int j=r; j<=m; j++)
{
res=max(res,s[i][j]-s[i-r][j]-s[i][j-r]+s[i-r][j-r]);
}
cout<<res;
return 0;
}