# -*- coding: utf-8 -*-
N =input()
item = [0] * 10
for i in range(N):
    tmp = map(int, raw_input().split())
    for j in range(3):
        item[tmp[j]-1] += 1

cnt1 = 0
cnt2 = 0
for i in range(10):
    cnt1 += item[i] // 2
    cnt2 += item[i] % 2
print cnt1 + cnt2 // 4