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

ans = 0
for i in range(10):
    ans += cnt[i]//2

# 合計3Nあって、ans*2 を消費済み
ans += (3*N - 2*ans)//4
print(ans)