import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);

        String str=sc.nextLine();
        String first=str.substring(str.indexOf(",")+1);
        String strart=first.substring(0,first.indexOf(","));        

        String end=str.substring(str.lastIndexOf(",")+1);
        Long count= Long.valueOf(end) - Long.valueOf(strart) -1;
        System.out.println(count);
    

      

    }
}