A friend of mine believes a lot in fate n all. He thinks 4 and 7 are lucky digits, and all other digits are not lucky. He has a definition for lucky numbers as well. A lucky number is a number that contains only lucky digits in decimal notation. All others are unlucky as per him.

He wants to know how many lucky numbers are there between two given numbers. I want u all to help him in this.



The input consists of several test cases. Each line of a test case consists of two numbers separated by a space: a and b. Both the numbers will be between 1 and 1,000,000,000, inclusive.



For each input line, determine the number of lucky numbers between a and b, inclusive.


Sample Input

1 10

74 77

1000000 5000000


Sample Output





using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Diagnostics;


namespace Luck


    class Program


        static void Main(string[] args)


            int a = 1000000;

            int b = 5000000;

            int count = 0;

            for (; a <= b; a++)


                string str = a.ToString();

                int flag = 0;

                for (int i = 0; i < str.Length; i++)


                    if (str[i].ToString() != "4")


                        if (str[i].ToString() != "7")


                            flag = 1;





                if (flag == 0)






            Console.WriteLine("Number of lucky numbers = " + count.ToString());




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