import java.util.Scanner;
public class No29 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int[] su = new int[10];
		int lvUp = 0;
		int itemCount = 0;
		int n = sc.nextInt();
		for(int i = 0; i < n * 3; i++){
			int getItem = sc.nextInt();
			itemCount++;
			// 同じアイテムが2つ揃う
			if(su[getItem - 1] == 1){	
				lvUp++;
				su[getItem - 1] = 0;
				itemCount -= 2;  	// 2つのアイテムを消費
			}else{
				su[getItem - 1]++;
			}
		}
		System.out.println(lvUp + (int)itemCount / 4);
		sc.close();

	}
}