import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int a = scan.nextInt();
        int b = scan.nextInt();
        int count = 0; //记录符合条件的个数
        for(int i = a; i <= b; i++){
            int num = i;
            int sum = 0; //记录个数数为之和
            while(num != 0){
                sum += num % 10;
                num /= 10;
            }
            if(sum % 5 == 0){
                count++;
            }
        }
        System.out.println(count);
    }
}