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: Wrong Answer)


#include <iostream>

using namespace std;

int main() {

	int a, b;

	int pa[1000] = { -1 };
	int pb[1000] = { -1 };

	int flag = 0;

	cin >> a >> b;

	for (int loop = 1; loop < 1400; loop++) {

		if ((int)(loop * 0.08) == a && flag<1000) {
			pa[flag] = loop;
			flag++;
		}
	}

	flag = 0;
	for (int loop = 1; loop < 1400; loop++) {

		if ((int)(loop * 0.1) == b && flag < 1000) {
			pb[flag] = loop;
			flag++;
		}
	}

	for (int xloop = 0; xloop < 1000; xloop++) {

		for (int yloop = 0; yloop < 1000; yloop++) {

			if (pa[xloop] != -1 && pa[xloop] == pb[yloop]) {

				cout << pa[xloop] << flush;
				return 0;
			}
		}
	}

	cout << -1;
	return 0;
}