def zip(X):
    l = list(set(X))
    l.sort()
    ma = l[-1]
    d = {x: i + 1 for i, x in enumerate(l)}
    return [d[x] for x in X], d[ma] + 1


def solve(N, B, X, Y, P):
    X, ma_x = zip(X)
    Y, ma_y = zip(Y)

    M = [[0] * ma_x for i in range(ma_y)]

    for i in range(N):
        M[Y[i]][X[i]] = P[i]

    S = [[0] * ma_x for i in range(ma_y)]
    C = [[0] * ma_x for i in range(ma_y)]

    for y in range(1, ma_y):
        sy1 = S[y - 1]
        cy1 = C[y - 1]
        my = M[y]
        sy = S[y]
        cy = C[y]

        for x in range(1, ma_x):
            m = my[x]
            sy[x] = sy[x - 1] + sy1[x] - sy1[x - 1] + m
            if m:
                cy[x] = cy[x - 1] + cy1[x] - cy1[x - 1] + 1
            else:
                cy[x] = cy[x - 1] + cy1[x] - cy1[x - 1]

    ma = 0
    for y1 in range(0, ma_y):
        sy1 = S[y1]
        cy1 = C[y1]
        for y2 in range(y1 + 1, ma_y):
            sy2 = S[y2]
            cy2 = C[y2]
            x1 = 0
            x2 = 1
            while x2 < ma_x:
                s = sy2[x2] - sy2[x1] - sy1[x2] + sy1[x1]
                if s <= B:
                    c = cy2[x2] - cy2[x1] - cy1[x2] + cy1[x1]
                    ma = max(ma, c)
                    x2 += 1
                else:
                    if x1 == x2:
                        x2 += 1
                    else:
                        x1 += 1

    print(ma)


def main():
    N, B = list(map(int, input().split()))
    X = [0] * N
    Y = [0] * N
    P = [0] * N
    for i in range(N):
        x, y, p = list(map(int, input().split()))
        X[i] = x
        Y[i] = y
        P[i] = p
    solve(N, B, X, Y, P)


if __name__ == '__main__':
    main()