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.*;
import java.util.*;
import java.math.*;

public class Main implements Runnable {
	private BufferedReader in;
	private PrintWriter out;
	private StringTokenizer st;
	private Random rnd;
	
	final long[] numbers = {4, 7, 44, 47, 74, 77, 444, 447, 474, 477, 744, 747, 774, 777, 4444, 4447, 4474, 4477, 4744, 4747, 4774, 4777, 7444, 7447, 7474, 7477, 7744, 7747, 7774, 7777, 44444, 44447, 44474, 44477, 44744, 44747, 44774, 44777, 47444, 47447, 47474, 47477, 47744, 47747, 47774, 47777, 74444, 74447, 74474, 74477, 74744, 74747, 74774, 74777, 77444, 77447, 77474, 77477, 77744, 77747, 77774, 77777, 444444, 444447, 444474, 444477, 444744, 444747, 444774, 444777, 447444, 447447, 447474, 447477, 447744, 447747, 447774, 447777, 474444, 474447, 474474, 474477, 474744, 474747, 474774, 474777, 477444, 477447, 477474, 477477, 477744, 477747, 477774, 477777, 744444, 744447, 744474, 744477, 744744, 744747, 744774, 744777, 747444, 747447, 747474, 747477, 747744, 747747, 747774, 747777, 774444, 774447, 774474, 774477, 774744, 774747, 774774, 774777, 777444, 777447, 777474, 777477, 777744, 777747, 777774, 777777, 4444444, 4444447, 4444474, 4444477, 4444744, 4444747, 4444774, 4444777, 4447444, 4447447, 4447474, 4447477, 4447744, 4447747, 4447774, 4447777, 4474444, 4474447, 4474474, 4474477, 4474744, 4474747, 4474774, 4474777, 4477444, 4477447, 4477474, 4477477, 4477744, 4477747, 4477774, 4477777, 4744444, 4744447, 4744474, 4744477, 4744744, 4744747, 4744774, 4744777, 4747444, 4747447, 4747474, 4747477, 4747744, 4747747, 4747774, 4747777, 4774444, 4774447, 4774474, 4774477, 4774744, 4774747, 4774774, 4774777, 4777444, 4777447, 4777474, 4777477, 4777744, 4777747, 4777774, 4777777, 7444444, 7444447, 7444474, 7444477, 7444744, 7444747, 7444774, 7444777, 7447444, 7447447, 7447474, 7447477, 7447744, 7447747, 7447774, 7447777, 7474444, 7474447, 7474474, 7474477, 7474744, 7474747, 7474774, 7474777, 7477444, 7477447, 7477474, 7477477, 7477744, 7477747, 7477774, 7477777, 7744444, 7744447, 7744474, 7744477, 7744744, 7744747, 7744774, 7744777, 7747444, 7747447, 7747474, 7747477, 7747744, 7747747, 7747774, 7747777, 7774444, 7774447, 7774474, 7774477, 7774744, 7774747, 7774774, 7774777, 7777444, 7777447, 7777474, 7777477, 7777744, 7777747, 7777774, 7777777, 44444444, 44444447, 44444474, 44444477, 44444744, 44444747, 44444774, 44444777, 44447444, 44447447, 44447474, 44447477, 44447744, 44447747, 44447774, 44447777, 44474444, 44474447, 44474474, 44474477, 44474744, 44474747, 44474774, 44474777, 44477444, 44477447, 44477474, 44477477, 44477744, 44477747, 44477774, 44477777, 44744444, 44744447, 44744474, 44744477, 44744744, 44744747, 44744774, 44744777, 44747444, 44747447, 44747474, 44747477, 44747744, 44747747, 44747774, 44747777, 44774444, 44774447, 44774474, 44774477, 44774744, 44774747, 44774774, 44774777, 44777444, 44777447, 44777474, 44777477, 44777744, 44777747, 44777774, 44777777, 47444444, 47444447, 47444474, 47444477, 47444744, 47444747, 47444774, 47444777, 47447444, 47447447, 47447474, 47447477, 47447744, 47447747, 47447774, 47447777, 47474444, 47474447, 47474474, 47474477, 47474744, 47474747, 47474774, 47474777, 47477444, 47477447, 47477474, 47477477, 47477744, 47477747, 47477774, 47477777, 47744444, 47744447, 47744474, 47744477, 47744744, 47744747, 47744774, 47744777, 47747444, 47747447, 47747474, 47747477, 47747744, 47747747, 47747774, 47747777, 47774444, 47774447, 47774474, 47774477, 47774744, 47774747, 47774774, 47774777, 47777444, 47777447, 47777474, 47777477, 47777744, 47777747, 47777774, 47777777, 74444444, 74444447, 74444474, 74444477, 74444744, 74444747, 74444774, 74444777, 74447444, 74447447, 74447474, 74447477, 74447744, 74447747, 74447774, 74447777, 74474444, 74474447, 74474474, 74474477, 74474744, 74474747, 74474774, 74474777, 74477444, 74477447, 74477474, 74477477, 74477744, 74477747, 74477774, 74477777, 74744444, 74744447, 74744474, 74744477, 74744744, 74744747, 74744774, 74744777, 74747444, 74747447, 74747474, 74747477, 74747744, 74747747, 74747774, 74747777, 74774444, 74774447, 74774474, 74774477, 74774744, 74774747, 74774774, 74774777, 74777444, 74777447, 74777474, 74777477, 74777744, 74777747, 74777774, 74777777, 77444444, 77444447, 77444474, 77444477, 77444744, 77444747, 77444774, 77444777, 77447444, 77447447, 77447474, 77447477, 77447744, 77447747, 77447774, 77447777, 77474444, 77474447, 77474474, 77474477, 77474744, 77474747, 77474774, 77474777, 77477444, 77477447, 77477474, 77477477, 77477744, 77477747, 77477774, 77477777, 77744444, 77744447, 77744474, 77744477, 77744744, 77744747, 77744774, 77744777, 77747444, 77747447, 77747474, 77747477, 77747744, 77747747, 77747774, 77747777, 77774444, 77774447, 77774474, 77774477, 77774744, 77774747, 77774774, 77774777, 77777444, 77777447, 77777474, 77777477, 77777744, 77777747, 77777774, 77777777, 444444444, 444444447, 444444474, 444444477, 444444744, 444444747, 444444774, 444444777, 444447444, 444447447, 444447474, 444447477, 444447744, 444447747, 444447774, 444447777, 444474444, 444474447, 444474474, 444474477, 444474744, 444474747, 444474774, 444474777, 444477444, 444477447, 444477474, 444477477, 444477744, 444477747, 444477774, 444477777, 444744444, 444744447, 444744474, 444744477, 444744744, 444744747, 444744774, 444744777, 444747444, 444747447, 444747474, 444747477, 444747744, 444747747, 444747774, 444747777, 444774444, 444774447, 444774474, 444774477, 444774744, 444774747, 444774774, 444774777, 444777444, 444777447, 444777474, 444777477, 444777744, 444777747, 444777774, 444777777, 447444444, 447444447, 447444474, 447444477, 447444744, 447444747, 447444774, 447444777, 447447444, 447447447, 447447474, 447447477, 447447744, 447447747, 447447774, 447447777, 447474444, 447474447, 447474474, 447474477, 447474744, 447474747, 447474774, 447474777, 447477444, 447477447, 447477474, 447477477, 447477744, 447477747, 447477774, 447477777, 447744444, 447744447, 447744474, 447744477, 447744744, 447744747, 447744774, 447744777, 447747444, 447747447, 447747474, 447747477, 447747744, 447747747, 447747774, 447747777, 447774444, 447774447, 447774474, 447774477, 447774744, 447774747, 447774774, 447774777, 447777444, 447777447, 447777474, 447777477, 447777744, 447777747, 447777774, 447777777, 474444444, 474444447, 474444474, 474444477, 474444744, 474444747, 474444774, 474444777, 474447444, 474447447, 474447474, 474447477, 474447744, 474447747, 474447774, 474447777, 474474444, 474474447, 474474474, 474474477, 474474744, 474474747, 474474774, 474474777, 474477444, 474477447, 474477474, 474477477, 474477744, 474477747, 474477774, 474477777, 474744444, 474744447, 474744474, 474744477, 474744744, 474744747, 474744774, 474744777, 474747444, 474747447, 474747474, 474747477, 474747744, 474747747, 474747774, 474747777, 474774444, 474774447, 474774474, 474774477, 474774744, 474774747, 474774774, 474774777, 474777444, 474777447, 474777474, 474777477, 474777744, 474777747, 474777774, 474777777, 477444444, 477444447, 477444474, 477444477, 477444744, 477444747, 477444774, 477444777, 477447444, 477447447, 477447474, 477447477, 477447744, 477447747, 477447774, 477447777, 477474444, 477474447, 477474474, 477474477, 477474744, 477474747, 477474774, 477474777, 477477444, 477477447, 477477474, 477477477, 477477744, 477477747, 477477774, 477477777, 477744444, 477744447, 477744474, 477744477, 477744744, 477744747, 477744774, 477744777, 477747444, 477747447, 477747474, 477747477, 477747744, 477747747, 477747774, 477747777, 477774444, 477774447, 477774474, 477774477, 477774744, 477774747, 477774774, 477774777, 477777444, 477777447, 477777474, 477777477, 477777744, 477777747, 477777774, 477777777, 744444444, 744444447, 744444474, 744444477, 744444744, 744444747, 744444774, 744444777, 744447444, 744447447, 744447474, 744447477, 744447744, 744447747, 744447774, 744447777, 744474444, 744474447, 744474474, 744474477, 744474744, 744474747, 744474774, 744474777, 744477444, 744477447, 744477474, 744477477, 744477744, 744477747, 744477774, 744477777, 744744444, 744744447, 744744474, 744744477, 744744744, 744744747, 744744774, 744744777, 744747444, 744747447, 744747474, 744747477, 744747744, 744747747, 744747774, 744747777, 744774444, 744774447, 744774474, 744774477, 744774744, 744774747, 744774774, 744774777, 744777444, 744777447, 744777474, 744777477, 744777744, 744777747, 744777774, 744777777, 747444444, 747444447, 747444474, 747444477, 747444744, 747444747, 747444774, 747444777, 747447444, 747447447, 747447474, 747447477, 747447744, 747447747, 747447774, 747447777, 747474444, 747474447, 747474474, 747474477, 747474744, 747474747, 747474774, 747474777, 747477444, 747477447, 747477474, 747477477, 747477744, 747477747, 747477774, 747477777, 747744444, 747744447, 747744474, 747744477, 747744744, 747744747, 747744774, 747744777, 747747444, 747747447, 747747474, 747747477, 747747744, 747747747, 747747774, 747747777, 747774444, 747774447, 747774474, 747774477, 747774744, 747774747, 747774774, 747774777, 747777444, 747777447, 747777474, 747777477, 747777744, 747777747, 747777774, 747777777, 774444444, 774444447, 774444474, 774444477, 774444744, 774444747, 774444774, 774444777, 774447444, 774447447, 774447474, 774447477, 774447744, 774447747, 774447774, 774447777, 774474444, 774474447, 774474474, 774474477, 774474744, 774474747, 774474774, 774474777, 774477444, 774477447, 774477474, 774477477, 774477744, 774477747, 774477774, 774477777, 774744444, 774744447, 774744474, 774744477, 774744744, 774744747, 774744774, 774744777, 774747444, 774747447, 774747474, 774747477, 774747744, 774747747, 774747774, 774747777, 774774444, 774774447, 774774474, 774774477, 774774744, 774774747, 774774774, 774774777, 774777444, 774777447, 774777474, 774777477, 774777744, 774777747, 774777774, 774777777, 777444444, 777444447, 777444474, 777444477, 777444744, 777444747, 777444774, 777444777, 777447444, 777447447, 777447474, 777447477, 777447744, 777447747, 777447774, 777447777, 777474444, 777474447, 777474474, 777474477, 777474744, 777474747, 777474774, 777474777, 777477444, 777477447, 777477474, 777477477, 777477744, 777477747, 777477774, 777477777, 777744444, 777744447, 777744474, 777744477, 777744744, 777744747, 777744774, 777744777, 777747444, 777747447, 777747474, 777747477, 777747744, 777747747, 777747774, 777747777, 777774444, 777774447, 777774474, 777774477, 777774744, 777774747, 777774774, 777774777, 777777444, 777777447, 777777474, 777777477, 777777744, 777777747, 777777774, 777777777, 4444444444L};
	
	
	public void solve() throws IOException {
		long l = nextLong(), r = nextLong();
		long res = 0;
		
		for(long number : numbers) {
			long cur = Math.min(number, r);
			if(l <= cur) {
				long how_much = cur - l + 1;
				l = cur + 1;
				res += number * how_much;
			}
		}
		
		out.println(res);
	}
		
	public static void main(String[] args) {
		new Main().run();
	} 
	
	public void run() {
		try {
			//in = new BufferedReader(new FileReader("E.IN"));
			//out = new PrintWriter(new FileWriter("output.txt"));
			
			in = new BufferedReader(new InputStreamReader((System.in)));
			out = new PrintWriter(System.out);
			
			st = null;
			rnd = new Random();
			
			solve();
			
			out.close();
		} catch(IOException e) {
			e.printStackTrace();
		}	
	}
	
	private String nextToken() throws IOException, NullPointerException {
		while(st == null || !st.hasMoreTokens()) {
			st = new StringTokenizer(in.readLine());
		}
		
		return st.nextToken();
	}
	
	private int nextInt() throws IOException {
		return Integer.parseInt(nextToken());
	}
	
	private long nextLong() throws IOException {
		return Long.parseLong(nextToken());
	}
	
	private double nextDouble() throws IOException {
		return Double.parseDouble(nextToken());
	}

}