item = [0] * 10
pu = 0
N = int(input())
for i in range(N):
    a, b, c = list(map(int, input().split()))
    item[a - 1] += 1
    item[b - 1] += 1
    item[c - 1] += 1

for i in range(10):
    while item[i] >= 2:
        item[i] -= 2
        pu += 1

s = sum(item)
while s >= 4:
    s -= 4
    pu += 1

print(pu)