n = int(input())

item = [0] * 10

for i in range(n):
    a, b, c = map(int, input().split())
    item[a-1] += 1
    item[b-1] += 1
    item[c-1] += 1

s, t = 0, 0
for i in item:
    s += i // 2
    t += i % 2

print(s + t // 4)