def main():
    N = int(input())
    dic = set()
    cnt = 0

    for i in range(N):
        abc = list(map(int, input().split()))
        for v in abc:
            if v in dic:
                cnt += 1
                dic.remove(v)
            else:
                dic.add(v)

    cnt += len(dic) // 4
    print(cnt)

main()