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) {
		try(Scanner scan = new Scanner(System.in)){
			int A = scan.nextInt();
			int B = scan.nextInt();
			
			double adashi = A*100/8;//それぞれ税抜き価格を求める小数点は切り捨て
			int a = (int)adashi;//A奇数の時点で終了
			int b = (int)B*100/10;
			int answer;
			
			
		
			if(A%2==1) {//Aが奇数ならやる必要がない
				System.out.println(-1);
			}else {
				
				if(a==b) {//もしa=bならとりあえず仮の答えが見つか
					answer =a;
					int X = a;
					while(X>0) {
						X--;
						int c = (int)X*8/100;
						int d = (int)X*10/100;
						if(c==A&&d==B) {
							answer = X;
							}
						
						
						}
					
					System.out.println(answer);
				
				}else{
					if(a>b) {
						if((int)(a*10/100)==B) {
							answer = a;
							System.out.println(answer);
						}else {
							System.out.println(-1);
						}
						
					}
					if(a<b) {
						if((int)(b*8/100)==A) {
							answer = b;
							System.out.println(answer);
						}else {
							System.out.println(-1);
						}
						
					}
					
				
			}
			
			}
		
		
		}	
	}
}