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: Wrong Answer)

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        // 入力データの取得
        Scanner scanner = new Scanner(System.in);
        String inputData = scanner.nextLine();
        scanner.close();

        //データの加工
        String[] editedInputData = inputData.split(" ");
        int smallerTax = Integer.parseInt(editedInputData[0]);
        int biggerTax = Integer.parseInt(editedInputData[1]);

        // 税抜き価格の算出
        double taxA = 0.08;
        double taxB = 0.10;
        int noTaxAUnderLimit = (int) (smallerTax / taxA);
        int noTaxAUpperLimit = (int) ((smallerTax + 1) / taxA);
        int noTaxBUnderLimit = (int) (biggerTax / taxB);
        int noTaxBUpperLimit = (int) ((biggerTax + 1) / taxB);

        // 判定
        if (noTaxAUnderLimit >= noTaxBUnderLimit && noTaxAUnderLimit < noTaxBUpperLimit) {
            System.out.println(noTaxAUnderLimit);
        } else if (noTaxBUnderLimit >= noTaxAUnderLimit && noTaxBUnderLimit < noTaxAUpperLimit) {
            System.out.println(noTaxBUnderLimit);
        } else {
            System.out.println("-1");
        }
        

    }

}