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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*; 

class Main{
public static void main(String[] args){
	Scanner sc=new Scanner(System.in);
      	int a=sc.nextInt();
        int b=sc.nextInt();
  		double a1=(double)a/0.08;
        double b1=(double)b/0.1;
  		int a2=(int)Math.ceil(a1);
        int b2=(int)Math.ceil(b1);
  		int ans=0;
  		
  		if(a2==b2){
        	ans=a2;
        }else if(a2<b2){
          if(Math.floor(b2*0.08)==(double)a){
          	ans=b2;
          }else{
          	ans=-1;
          }
        }else{
          if(Math.floor(a2*0.1)==(double)b){
          	ans=a2;
          }else{
          	ans=-1;
          }
        }
  		
    
 	

    	System.out.println(ans);
    }
}