#coding=UTF-8

#ついにNo.1の問題に手をつける
N=int(input())
inventory=[0]*10#スペルの保証はしない

for idx in range(0,N,1):
    mojir=input()
    hyo=mojir.split(' ')
    for idy in range(0,3,1):
        inventory[int(hyo[idy])-1]=inventory[int(hyo[idy])-1]+1

#print(inventory)
#greedyでOK?
ans=0
for idx in range(0,10,1):
    ans=ans+inventory[idx]//2
    inventory[idx]=inventory[idx]%2

ans=ans+sum(inventory)//4
print(ans)