import java.util.Scanner;
 
public class InternvalZeZadanych{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int count = 0;
        while(true){
            int i = sc.nextInt();
            if(i!=0){
                if(i<=20 && i>=10){
                    count++;
                }
            }else{
                System.out.println("Pocet ci­sel z intervalu: "+count);
                break;
            }
        }
    }
}