N=int(raw_input())
L=[0 for a in range(10)]
ct=0
for n in range(N):
    a, b, c=map(int, raw_input().split())
    L[a-1]+=1
    L[b-1]+=1
    L[c-1]+=1

for m in range(10):
    if L[m]>=2:
        ct+=L[m]/2
        L[m]%=2


S=sum(L)
ct+=S/4
print ct