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.*;
public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();
		int As = (A * 100 + 7) / 8;
		int Al = ((A+1) * 100 - 1) / 8;
		int Bs = B * 10;
		int Bl = ((B+1) * 100 - 1) / 10;
		if(Bs <= Al && As <= Bl) {
			int ans = As;
			while(true) {
				if(ans >= Bs)
					break;
				ans++;
			}
			System.out.println(ans);
		}
		else 
			System.out.println(-1);
	}

}