battle = int(input())
items = [0]*11

powerUp = 0
option = 0

for i in range(battle):
    get_item = list(map(int, input().split()))

    for j in range(3):
        items[get_item[j]] += 1

for item in items:
    
    powerUp += int(item/2)
    item = item%2
    
    option += item
    
powerUp += int(option/4)
print(powerUp)