Find the price of a product before tax such that, when the consumption tax rate is 8 percent and 10 percent, the amount of consumption tax levied on it is A yen and B yen, respectively. (Yen is the currency of Japan.)

Here, the price before tax must be a positive integer, and the amount of consumption tax is rounded down to the nearest integer.

If multiple prices satisfy the condition, print the lowest such price; if no price satisfies the condition, print `-1`.

Constraints

* 1 \leq A \leq B \leq 100
* A and B are integers.

Input

Input is given from Standard Input in the following format:


A B


Output

If there is a price that satisfies the condition, print an integer representing the lowest such price; otherwise, print `-1`.

Examples

Input

2 2


Output

25


Input

8 10


Output

100


Input

19 99


Output

-1

import java.util.Scanner;

public class Main{

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int a = Integer.parseInt(sc.next());
		int b = Integer.parseInt(sc.next());
	;
		int max = (int) Math.max(a,b);
		int ans= -1;
		for(int i = max ; i < 10001 ;i ++) {
			if(Math.floorDiv(i*2, 25) == a && Math.floorDiv(i, 10) == b ) {
				ans = i;
				break;
			}
			}
		System.out.println(ans);
	}
	
}
