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 <bits/stdc++.h>

using namespace std;


int main()
{
	int A, B;
	cin >> A >> B;
	map<int, int> result;
	float ApNum = ((float)A + 1.0f) / 0.08f;
	float ANum = (float)A / 0.08f;
	int Anum1 = ceil(ANum);
	int Anum2 = floor(ApNum - 0.0000001);
	
	int error = -1;
	float BpNum = ((float)B + 1.0f) / 0.1f;
	float BNum = (float)B / 0.1f;
	int Bnum1 = ceil(BNum);
	int Bnum2 = floor(BpNum - 0.0000001);

	if (Anum1 < Bnum1 && Anum2 < Bnum1) {
		cout << error << endl;
		return 0;
	}

	if (Anum1 > Bnum1 && Bnum2 < Anum1) {
		cout << error << endl;
		return 0;
	}

	int minval = max(Anum1, Bnum1);
	int maxval = min(Anum2, Bnum2);
	minval = min(minval, maxval);

	cout << minval << endl;

	return 0;



}