Petya loves lucky numbers. Everybody knows that lucky numbers are positive integers whose decimal representation contains only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

Let next(x) be the minimum lucky number which is larger than or equals x. Petya is interested what is the value of the expression next(l) + next(l + 1) + ... + next(r - 1) + next(r). Help him solve this problem.

Input

The single line contains two integers l and r (1 ≤ l ≤ r ≤ 109) — the left and right interval limits.

Output

In the single line print the only number — the sum next(l) + next(l + 1) + ... + next(r - 1) + next(r).

Please do not use the %lld specificator to read or write 64-bit integers in C++. It is preferred to use the cin, cout streams or the %I64d specificator.

Examples

Input

2 7


Output

33


Input

7 7


Output

7

Note

In the first sample: next(2) + next(3) + next(4) + next(5) + next(6) + next(7) = 4 + 4 + 4 + 7 + 7 + 7 = 33

In the second sample: next(7) = 7
import java.io.BufferedReader;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.*;

public class C {

	static boolean test = false;

	long max = 4444444444L;
	
	private void solve() throws Throwable {
		go("");
		numbers.add(0L);
		Collections.sort(numbers);
		
		long min = lread();
		long max = lread();
		long sum = 0;
		
		int status = 0;
		
		for (int i = 0; i < numbers.size(); i++) {
			Long lucky = numbers.get(i);
			
			if(status == 0 && min <= lucky){
				sum += lucky * (lucky - min + 1);
				status = 1;
			} else if(status == 1){
				sum += lucky*(lucky - numbers.get(i-1));	 
			}
			
			if(status == 1 && lucky > max){
				sum -= lucky * (lucky - max);
				status = 2;
			}
//			System.out.println(sum);
//			System.out.println(numbers.get(i));
		}
		
		System.out.println(sum);
	}
	
	List<Long> numbers = new ArrayList<Long>();
	
	private void go(String string) {
		String four = string + "4";
		String seven = string + "7";
		Long v4 = Long.valueOf(four);
		Long v7 = Long.valueOf(seven);
		
		if(v4 <= max){
			numbers.add(v4);
			go(four);
		}
		if(v7 <= max){
			numbers.add(v7);
			go(seven);
		}
	}

	public int iread() throws Exception {
		return Integer.parseInt(wread());
	}

	public double dread() throws Exception {
		return Double.parseDouble(wread());
	}

	public long lread() throws Exception {
		return Long.parseLong(wread());
	}

	public String wread() throws IOException {
		StringBuilder b = new StringBuilder();
		int c;
		c = in.read();
		while (c >= 0 && c <= ' ')
			c = in.read();
		if (c < 0)
			return "";
		while (c > ' ') {
			b.append((char) c);
			c = in.read();
		}
		return b.toString();
	}

	public static void main(String[] args) throws Throwable {
		new C().solve();
		out.close();
	}

	public C() throws Throwable {
		if (test) {
			in = new BufferedReader(new FileReader(new File(testDataFile)));
		} else {
			new BufferedReader(inp);
		}
	}

	static InputStreamReader inp = new InputStreamReader(System.in);
	static BufferedReader in = new BufferedReader(inp);
	static BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));

	static String testDataFile = "testdata.txt";
	BufferedReader reader = null;
}