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

X=[]
Y=[]

for x,y,_ in P:
    X.append(x)
    Y.append(y)

X=sorted(set(X))
Y=sorted(set(Y))

DX={X[i]:i for i in range(len(X))}
DY={Y[i]:i for i in range(len(Y))}

for i in range(N):
    P[i][0]=DX[P[i][0]]
    P[i][1]=DY[P[i][1]]


MAP=[[0]*(len(Y)+3) for i in range(len(X)+3)]
MAPP=[[0]*(len(Y)+3) for i in range(len(X)+3)]

for x,y,p in P:
    MAP[x][y]+=p
    MAPP[x][y]+=1

for i in range(1,len(X)+2):
    for j in range(len(Y)+2):
        MAP[i][j]+=MAP[i-1][j]
        MAPP[i][j]+=MAPP[i-1][j]

for i in range(len(X)+2):
    for j in range(1,len(Y)+2):
        MAP[i][j]+=MAP[i][j-1]
        MAPP[i][j]+=MAPP[i][j-1]

ANS=0

for i in range(len(X)):
    for j in range(i,len(X)):
        rind=0

        for lind in range(len(Y)):
            while rind<len(Y):
                if MAP[j][rind]-MAP[j][lind-1]-MAP[i-1][rind]+MAP[i-1][lind-1]<=B:
                    ANS=max(ANS,MAPP[j][rind]-MAPP[j][lind-1]-MAPP[i-1][rind]+MAPP[i-1][lind-1])
                    rind+=1
                else:
                    break

print(ANS)