n=int(input())
arr=[0,0,0,0,0,0,0,0,0,0]
for i in range(0,n):
    a,b,c=map(int,input().split())
    arr[a-1]+=1;
    arr[b-1]+=1;
    arr[c-1]+=1;
x=0
y=0
z=0
for i in range(0,10):
    d=arr[i]
    if(d>=2):
        while(1):
            int(d)
            if(d<2):
                y+=d
                break
            d-=2
            x+=1

    else:
        y+=d
y/=4
z=int(x)+int(y)
print(z)