#!/usr/bin/env python3
import sys
input = sys.stdin.readline

n = int(input())
cnt = [0] * 10
for _ in range(n):
    a, b, c = [int(item) - 1 for item in input().split()]
    cnt[a] += 1
    cnt[b] += 1
    cnt[c] += 1

rest = 0
ans = 0
for item in cnt:
    ans += item // 2
    rest += item % 2
ans += rest // 4
print(ans)