def sum(lst):
	cnt = 0
	for i in range(0, len(lst)):
		cnt += lst[i]
	return cnt

n = int(raw_input())
item = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
for i in range(0, n):
	inpt = map(int, raw_input().split())
	for j in range(0, 3):
		item[inpt[j]] += 1
		
cnt = 0
for i in range(0, 11):
	cnt += item[i] / 2
	item[i] = item[i] % 2

cnt += sum(item) / 4

print cnt