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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include<string>
#include<time.h>
#include<math.h>
#include<stdlib.h>
#include<map>
using namespace std;


int main() {
		int A, B;
		cin >> A >> B;
		double Amin, Amax,Bmin,Bmax;
		if (A % 2 == 0) {
			Amin = (A / 0.08);
			Amax = ((A + 1) / 0.08) - 0.5;
		}
		else {
			Amin = A / 0.08 + 0.5;
			Amax = ((A + 1) / 0.08) - 1;
		
		}

		Bmin = B / 0.1;
		Bmax = ((B + 1) / 0.1) - 1;

		//cout << Amin << endl << Amax << endl << Bmin << endl << Bmax << endl;

		if (Amax < Bmin || Bmax < Amin) {
			cout << -1 << endl;
		}
		else if (Amin <= Bmin && Bmin <= Amax) {
			cout << Bmin << endl;
		}
		else if (Bmin <= Amin && Amin <= Bmax) {
			cout << Amin << endl;
		}
		
	
	
		return 0;
}