import java.util.Scanner;
	

public class Main{
	
	
	public static void main(String args[])throws Exception{
		
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int[] item = new int[11];
		for(int i=0;i<3*N;i++){
			int I = sc.nextInt();
			item[I]++;
		}
		int ans = 0;
		int amari = 0;
		for(int i=1;i<=10;i++){
			ans += item[i]/2;
			amari += item[i]%2;
		}
		ans += amari/4;
		System.out.println(ans);
	}
}