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 = upCnt + (i / 2);// 同じアイテム2つでパワーアップ
			modCnt = modCnt + (i % 2);
		}
		upCnt = upCnt + (modCnt / 4);// 任意のアイテム4つでパワーアップ

		System.out.println(upCnt);
	}	
}