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.FileInputStream;
import java.io.InputStreamReader;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Collections;


public class C {
	
	public static int[] readNNumbers(BufferedReader bf, int n) throws Exception{
		int[] nums = new int[n];
		int idx = 0;
		
		String line = bf.readLine();
		for(int i = 0; i < line.length(); i++) {
			char c = line.charAt(i);
			if(c == ' ') idx++;
			else {
				int d = c - '0';
				nums[idx] = 10 * nums[idx] + d;
			}
		}
		
		return nums;
	}
	
	public static int[] readNums(BufferedReader bf) throws Exception {		
		int idx = 0, n = 0;		
		String line = bf.readLine();
		
		int i;
		for(i = 0; i < line.length(); i++) {
			char c = line.charAt(i);
			if(c == ' ') break;
			
			int d = c - '0';
			n = 10 * n + d;
		}
		
		int[] nums = new int[n];
		for(i = i + 1; i < line.length(); i++) {
			char c = line.charAt(i);
			if(c == ' ') idx++;
			else {
				int d = c - '0';
				nums[idx] = 10 * nums[idx] + d;
			}
		}
		
		return nums;
	}
	
	public static ArrayList<Long> luckyNumbers;
	public static long left, right;
	
	public static void genLuckyNumbers(long before) {
		long four = before * 10L + 4L;
		long seven = before * 10L + 7;
		
		if(four <= 100L * right) {
			luckyNumbers.add(four);
			genLuckyNumbers(four);
		}
		if(seven <= 100L * right) {
			luckyNumbers.add(seven);
			genLuckyNumbers(seven);
		}
	}
	
	public static void main(String[] args) throws Exception {
//		System.setIn(new FileInputStream("c.in"));
		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
		
		luckyNumbers = new ArrayList<Long>();
		int[] input = readNNumbers(bf, 2);
		left = input[0];
		right = input[1];
		
		genLuckyNumbers(0L);
		Collections.sort(luckyNumbers);
		
		long count = 0L;
		
		int i = 0;
		while(luckyNumbers.get(i) < left) i++;
		
		while(luckyNumbers.get(i) <= right) {
			long lucky = luckyNumbers.get(i);
			
			long actCount = lucky * (lucky - left + 1);
			
			left = lucky + 1;
			
			count += actCount;
			
			i++;
		}
		
		count += (right - left + 1) * luckyNumbers.get(i);
		
		System.out.println(count);
	}

}
