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 C# (.NET Core 3.1.201) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;

namespace test
{
    class MainClass
    {
        public static void Main(string[] args)
        {

            //問題158

            //A <= x * 1.08 < A + 1
            //100 * A <= x * 108 < 100 * A + 100
            //B * 100 <= x * 110 < B * 100 + 100

            //A * 100 / 108 <= x < (A + 100) / 108
            //B * 100 / 110 <= x < (B + 100) / 110

            //a <= x * 0.08

            string[] line = Console.ReadLine().Split(' ');
            int a = int.Parse(line[0]);
            int b = int.Parse(line[1]);

            for (int i = 1; i <= 100; i++)
            {
                if (100 * a <= i * 8 && i * 8 < 100 * a + 100)
                {
                    if (100 * b <= i * 10 && i * 10 < b * 100 + 100)
                    {
                        Console.WriteLine(i);
                        return;
                    }
                }
            }

            Console.WriteLine(-1);
        }

    }





    
}