N=int(input())
A=[0]*N
B=[0]*N
C=[0]*N
power=0
count=0

for i in range(N):
    A[i],B[i],C[i]=map(int,input().split())

Item=A+B+C

for x in range(1,11):
    element_num=Item.count(x)
    if (element_num%2)==0:
        power+=(element_num//2)
    else:
        power+=(element_num//2)
        count+=1
    if count==4:
        power+=1
        count=0

print(power)