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.Scanner;

public class Main{

    public static void main(String[] args) {

        new Main().solve();
    }

    void solve(){

        int a, b;

        Scanner sc = new Scanner(System.in);
        a = Integer.parseInt(sc.next());
        b = Integer.parseInt(sc.next());
        sc.close();

        double ataxfreemax, ataxfreemin; 
        double btaxfreemax, btaxfreemin;

        ataxfreemax = (a + 1) / 0.08;
        ataxfreemin = a / 0.08;
        btaxfreemax = (b + 1) / 0.1;
        btaxfreemin = b / 0.1;

        int amax, amin;
        if (Math.floor(ataxfreemax) == ataxfreemax){
            amax = (int) ataxfreemax - 1;
        }
        else {
            amax = (int) ataxfreemax;
        }

        if(Math.ceil(ataxfreemin) == ataxfreemin){
            amin = (int) ataxfreemin;
        }
        else{
            amin = (int) ataxfreemin + 1;
        }

        int bmax, bmin;
        if (Math.floor(btaxfreemax) == btaxfreemax){
            bmax = (int) btaxfreemax - 1;
        }
        else {
            bmax = (int) btaxfreemax;
        }

        if(Math.ceil(btaxfreemin) == btaxfreemin){
            bmin = (int) btaxfreemin;
        }
        else{
            bmin = (int) btaxfreemin + 1;
        }

        if(amax>bmax && bmax>amin){
            if(bmin>amin){
                System.out.println(bmin);
            }
            else{
                System.out.println(amin);
            }
        }
        else if(amax>bmin && bmin>amin){
            System.out.println(bmin);
        }
        else if(bmax>amax && amax>bmin){
            if(amin>bmin){
                System.out.println(amin);
            }
            else{
                System.out.println(bmin);
            }
        }
        else if(bmax>amin && amin>bmin){
            System.out.println(amin);
        }
        else{
            System.out.println("-1");
        }
    }
}