package me.yukicoder.lv1;
import java.util.Scanner;

public class No0029 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int[] items = new int[10];

		// アイテムを格納
		for (int i = 0; i < N * 3; i++) {
			int itemNum = sc.nextInt();
			items[itemNum - 1] = items[itemNum - 1] + 1;
		}

		int upCnt = 0;
		int modCnt = 0;
		for (int i : items) {
			upCnt += i / 2;
			modCnt += i % 2;
		}
		upCnt += modCnt / 4;
		System.out.println(upCnt);
	}	
}