N = int(input())
A = []
for n in range(N):
	X,Y,Z = map(int,input().split())
	V = X*Y*Z
	A.append([X,Y,Z,V])
A.sort(key = lambda x: - x[3])
B = [[float("inf") for i in range(3)] + [0]]
for a in A:
	for b in B:
		if b[0] > a[0] and b[1] > a[1] and b[2] > a[2]:
			B.append(a[:-1] + [b[3] + 1])
			B.sort(key = lambda x: - x[3])
			break
print(B[0][3])