implicit none
integer(8) i,n,m,j,a,b
integer(8),allocatable :: x(:,:)
integer(8),allocatable :: y(:)
read(*,*) n
allocate (x(1:n,1:3))
allocate (y(1:10))
x=0
y=0
a=0
b=0
do i=1,n
    read(*,*) (x(i,m),m=1,3)
    do j=1,3
        y(x(i,j))=y(x(i,j))+1
    end do
end do

do i=1,11
    if (y(i) >= 2) then
        do while (y(i) > 1)
            a = a+1
            y(i)=y(i)-2
        end do
    end if
end do

do i=1,11
    if (y(i) >=1 ) then
        b=b+1
    end if
end do

b=b/4

write(*,*) a+b
end