import java.util.Scanner;

class Main {
    public static void main(String[] args) throws Exception {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] num = new int[10];
        int lvUp = 0;
        int itemCnt = 0;
        for(int i=0; i<n*3; i++) {
            int getItem = in.nextInt();
            itemCnt++;
            if(num[getItem-1] == 1) {
                lvUp++;
                num[getItem-1] = 0;
                itemCnt -= 2;
            } else {
                num[getItem-1]++;
            }
        }
        System.out.println(lvUp + (int)itemCnt / 4);
    }
}