import numpy as np
import itertools

N, B = map(int, input().split())
P = [tuple(map(int, input().split())) for _ in range(N)]

set_x, set_y = set(), set()
for x, y, _ in P:
    set_x.add(x)
    set_y.add(y)
dict_x = {x: i for i, x in enumerate(sorted(list(set_x)))}
dict_y = {y: i for i, y in enumerate(sorted(list(set_y)))}

lx, ly = len(set_x), len(set_y)

score = np.zeros((ly + 1, lx + 1), dtype=np.int64)
point = np.zeros((ly + 1, lx + 1), dtype=np.int64)
for x, y, p in P:
    score[dict_y[y] + 1][dict_x[x] + 1] = p
    point[dict_y[y] + 1][dict_x[x] + 1] = 1

np.cumsum(score, axis=0, out=score)
np.cumsum(score, axis=1, out=score)
score = score.tolist()

np.cumsum(point, axis=0, out=point)
np.cumsum(point, axis=1, out=point)
point = point.tolist()

ans = 0
for u, d in itertools.combinations(range(ly + 1), 2):
    l = 0
    for r in range(1, lx + 1):
        while score[d][r] + score[u][l] - score[d][l] - score[u][r] > B:
            if r - l <= 1:
                break
            l += 1
        else:
            ans = max(ans,
                      point[d][r] + point[u][l] - point[d][l] - point[u][r])
print(ans)