Problem:
Score : 300 points

Problem Statement

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.

Sample Input 1

2 2

Sample Output 1

25

If the price of a product before tax is 25 yen, the amount of consumption tax levied on it is:

When the consumption tax rate is 8 percent: \lfloor 25 \times 0.08 \rfloor = \lfloor 2 \rfloor = 2 yen.

When the consumption tax rate is 10 percent: \lfloor 25 \times 0.1 \rfloor = \lfloor 2.5 \rfloor = 2 yen.

Thus, the price of 25 yen satisfies the condition. There are other possible prices, such as 26 yen, but print the minimum such price, 25.

Sample Input 2

8 10

Sample Output 2

100

If the price of a product before tax is 100 yen, the amount of consumption tax levied on it is:

When the consumption tax rate is 8 percent: \lfloor 100 \times 0.08 \rfloor = 8 yen.

When the consumption tax rate is 10 percent: \lfloor 100 \times 0.1 \rfloor = 10 yen.

Sample Input 3

19 99

Sample Output 3

-1

There is no price before tax satisfying this condition, so print -1.

Solution in Java (OpenJDK 11.0.6) (judge verdict: Wrong Answer)

import java.util.*;
import java.lang.Math;

public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
  		
      	int a = sc.nextInt();
      	int b = sc.nextInt();
      	int stack;
      	
      	a *= 100;
      	if((a/100)%2==1) a+=4;
      	b *= 100;
      
      	boolean b1 = (a+96)*100/8 < b*100/10;
      	if((a+96)%100 == 0) b1 = (a+88)*100/8 < b*100/10;
      	boolean b2 = (b+90)*100/10 < a*100/8;
      	boolean b3 = a/100/8 < b/100/10;
      
      	if(b1 || b2) System.out.println(-1);
      	else if(b3) {
          stack = b*100/10/100;
          if((int)(stack * 0.08) == a /100) System.out.println(stack);
          else System.out.println(stack + 1);
        }
        else if(!b3) {
          stack = a*100/8/100;
          if((int)(stack * 0.1) == b/100) System.out.println(stack);
          else System.out.println(stack + 1);
        }
        
	}
}