import java.util.*;
class No29{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int One = 0;
		int Two = 0;
		int Three = 0;
		int Four = 0;
		int Five = 0;
		int Six = 0;
		int Seven = 0;
		int Eight = 0;
		int Nine = 0;
		int[][] num = new int[N][3];
		
		for(int i=0; i<N; i++){
			for(int j=0; j<3; j++){
				num[i][j] = sc.nextInt();
				if(num[i][j] == 1){
					One++;
				}else if(num[i][j] == 2){
					Two++;
				}else if(num[i][j] == 3){
					Three++;
				}else if(num[i][j] == 4){
					Four++;
				}else if(num[i][j] == 5){
					Five++;
				}else if(num[i][j] == 6){
					Six++;
				}else if(num[i][j] == 7){
					Seven++;
				}else if(num[i][j] == 8){
					Eight++;
				}else if(num[i][j] == 9){
					Nine++;
				}
			}
		}
		One = (int)Math.floor(One/2);
		Two = (int)Math.floor(Two/2);
		Three = (int)Math.floor(Three/2);
		Four = (int)Math.floor(Four/2);
		Five = (int)Math.floor(Five/2);
		Six = (int)Math.floor(Six/2);
		Seven = (int)Math.floor(Seven/2);
		Eight = (int)Math.floor(Eight/2);
		Nine = (int)Math.floor(Nine/2);
		int Sum = One+Two+Three+Four+Five+Six+Seven+Eight+Nine;
		System.out.println(Sum);
	}
}