# No.29 パワーアップ
N = int(input())
items = [0] * 10
powerUps = 0
other_items = 0

for i in range(N):
    get_items = [int(i) for i in input().split()]

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

for i in range(10):
    powerUps += items[i] // 2
    items[i] %= 2

print(powerUps + sum(items) // 4)