import java.util.*;

public class Main{
        public static void main(String[] args){
                try(Scanner sc = new Scanner(System.in)){
                        int N = sc.nextInt();
                        int[] X = new int[100];
                        for(int i = 0; i < 3 * N; i++){
                                X[sc.nextInt() - 1]++;
                        }
                        int ans = 0, count = 0;
                        for(int i = 0; i < 100; i++){
                                ans += X[i] / 2;
                                count += X[i] % 2;
                        }
                        ans += count / 4;
                        System.out.println(ans);
                }
        }
}