integer::N,i,up=0,res=0
  integer::drop(300),item(10)=0
  read *, N
  read *, drop(1:3*N)
  do i=1, 3*N
     item(drop(i)) = item(drop(i)) + 1
  end do

  do i=1,10
     up  = up  + item(i)/2
     res = res + MOD(item(i),2)
  end do
  print '(i0)', up + res/4
end program