import java.util.*;

public class Exercise145{
  public static void main (String[] args){

    Scanner sc = new Scanner(System.in);

    int n = sc.nextInt();
    int[] array = new int[11];
    int a = 0;
    int h = 0;

    for(int i = 0; i < n * 3; i++){
      array[sc.nextInt()]++;
    }
    for(int i = 1; i < 11; i++){
      a += array[i] / 2;
      if(array[i] % 2 == 1){
        h++;
      }
    }
    System.out.println(a + h / 4);
  }
}