n = int(input())
lst = [0 for _ in range(11)]
for _ in range(n):
    a, b, c = map(int, input().split())
    lst[a] += 1
    lst[b] += 1
    lst[c] += 1
ans = 0
tmp = 0
for num in lst:
    ans += num // 2
    tmp += num % 2
print(ans + tmp // 4)