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: Runtime Error)

import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Scanner;

public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		int B = sc.nextInt();

		ArrayList<BigDecimal> arrayA = new ArrayList<>(10);
		ArrayList<BigDecimal> arrayB = new ArrayList<>(10);
		for(BigDecimal i = BigDecimal.ZERO; i.compareTo(BigDecimal.ONE) < 0; i = i.add(BigDecimal.valueOf(0.1))) {
			arrayA.add(BigDecimal.valueOf(A).add(i).divide(BigDecimal.valueOf(0.08)));
			arrayB.add(BigDecimal.valueOf(B).add(i).divide(BigDecimal.valueOf(0.10)));
		}

		boolean isNotExists = true;
		start : for(BigDecimal a : arrayA) {
			if(a.compareTo(a.setScale(0)) != 0) {
				continue;
			}
			for(BigDecimal b : arrayB) {
				if(b.compareTo(b.setScale(0)) != 0) {
					continue;
				}
				if(a.compareTo(b) == 0) {
					isNotExists = false;
					System.out.println(a.intValue());
					break start;
				}
			}
		}
		if(isNotExists) {
			System.out.println(-1);
		}

	}
}