#29 power up
N=int(input())
a=[[int(i) for i in input().split()] for i in range(N)]
ite=[0]*10
for i in range(3):
    for j in range(N):
        ite[a[i][j]]+=1
p=0
r=0
for i in range(10):
    p+=ite[i]//2
    r+=ite[i]%2
r//=4
p+=r
print(p)