N = int(input())
LI = []
for i in range(0,N) :
    a,b,c = map(int,input().split())
    LI.append(a)
    LI.append(b)
    LI.append(c)
ansA = 0
ansB = 0
for i in range(1,11) :
    number = int(LI.count(i))
    ansAi = number // 2
    ansBi = number % 2
    ansA += ansAi
    ansB += ansBi
print(ansA + ansB//4)