package luogu;
import java.util.Scanner;
public class P5728旗鼓相当的对手 {
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        int t=0;
        int n=sc.nextInt();
        int[] yu=new int[n];
        int[] shu=new int[n];
        int[] ying=new int[n];

        for(int i=0;i<n;i++){
            yu[i]=sc.nextInt();
            shu[i]=sc.nextInt();
            ying[i]=sc.nextInt();
        }

        for(int j=0;j<n-1;j++){
            if(Math.abs(yu[j]-yu[j+1])<=5&&
                    Math.abs(shu[j]-shu[j+1])<=5&&
                    Math.abs(ying[j]-ying[j+1])<=5&&
                    Math.abs((yu[j]+shu[j]+ying[j])-(yu[j+1]+shu[j+1]+ying[j+1]))<=10){

                t++;
            }
        }

System.out.println(t);

    }
}