n = int(input())
ls = [0] * 10
for i in range(n):
	a,b,c = map(int,input().split())
	ls[a-1] += 1
	ls[b-1] += 1
	ls[c-1] += 1
s = 0
t = 0
for i in ls:
	s += i // 2
	t += i % 2
s += t // 4
print(s)