n=int(input())
x=[]
for i in range(n):
    a,b,c=map(int,input().split())
    x.append(a)
    x.append(b)
    x.append(c)
y=[]
for i in range(1,11):
    y.append(x.count(i))
z=[2,2,2,2,2,2,2,2,2,2]
s = [c // d for (c, d) in zip(y, z)]
t = [c % d for (c, d) in zip(y, z)]
print(sum(s)+sum(t)//4)