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