#pragma GCC optimize("Ofast")
#include <iostream>
#include <vector>
#include <utility>
#include <set>
#include <list>
#include <cassert>
#include <queue>
#include <cmath>
#include <map>
#include <algorithm>

using namespace std;
using ll = long long int;
#define REP(i, n) for(int i = 0; i < (int)(n); i++)
#define YES(n) std::cout << ((n) ? "YES" : "NO"  ) << "\n";
#define Yes(n) std::cout << ((n) ? "Yes" : "No" ) << "\n";

#define ALL_INCLUDED_ENVIRONMENT

template <class T, class Alloc, template <class, class> class C> std::ostream& operator<<(std::ostream& o, const C<T, Alloc>& v) {
  o << "{";
  bool init = 1;
  for (auto e : v) {
    if (init) { init = 0; }
    else { o << ", "; }
    o << e;
  }
  o << "}";
  return o;
}

int n, b, sup, res;
vector<int> xs, ys, ps, table;
vector<vector<int> > cumuls, exists;

template <class T> inline T get_2dcumul(const vector<vector<T> >& cumuls, int y1, int x1, int y2, int x2) {
  return cumuls[y2][x2] - cumuls[y2][x1] - cumuls[y1][x2] + cumuls[y1][x1];
}

int main() {
  // cin.tie(0);
  // ios::sync_with_stdio(false);
  cin >> n >> b;
  REP (i, n) {
    int x, y, p;
    cin >> x >> y >> p;
    xs.push_back(x);
    ys.push_back(y);
    ps.push_back(p);
    table.push_back(x);
    table.push_back(y);
  }
  sort(table.begin(), table.end(), std::less<int>());
  table.erase(unique(table.begin(), table.end()), table.end());

  REP (i, n) {
    xs[i] = lower_bound(table.begin(), table.end(), xs[i]) - table.begin();
    ys[i] = lower_bound(table.begin(), table.end(), ys[i]) - table.begin();
  }
  
  sup = table.size();
  cumuls = vector<vector<int> >(sup+1, vector<int>(sup+1, 0));
  exists = vector<vector<int> >(sup+1, vector<int>(sup+1, 0));
  REP (i, n) {
    int x = xs[i];
    int y = ys[i];
    cumuls[y+1][x+1] += ps[i];
    exists[y+1][x+1] += 1;
  }
  REP (i, sup+1) {
    REP (j, sup) {
      cumuls[i][j+1] += cumuls[i][j];
      exists[i][j+1] += exists[i][j];
    }
  }
  REP (j, sup+1) {
    REP (i, sup) {
      cumuls[i+1][j] += cumuls[i][j];
      exists[i+1][j] += exists[i][j];
    }
  }

  res = 0;
  for (int y1 = 0; y1 <= sup; y1++) {
    for (int y2 = y1+1; y2 <= sup; y2++) {
      int x1 = 0;
      for (int x2 = 0; x2 <= sup; x2++) {
        while(get_2dcumul(cumuls, y1, x1, y2, x2) > b) {
          x1++;
        }
        res = max(res, get_2dcumul(exists, y1, x1, y2, x2));
      }
    }
  }

  cout << res << "\n";
  return 0;
}