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.*;
import java.io.*;
import java.util.stream.*;

public class Main{
	private static BufferedReader in;
	private static BufferedWriter out;
	
	public static void main(String[] args) throws IOException {
		open();

		StringTokenizer st;
		StringBuilder sb;
		
		st=new StringTokenizer(readString());
		int a=Integer.parseInt(st.nextToken());
		int b=Integer.parseInt(st.nextToken());
		double num1,num2;
		num1=a/.08;
		num2=b/.1;
		int aux=(int)num1;
		num1/=10;
		num2/=10;
		a=(int) Math.floor(num1);
		b=(int) Math.floor(num2);
		if(a==b)
			out.write(aux+"\n");
		else
			out.write(-1+"\n");
		
		close();
	}
	
	private static int[] readInts() throws IOException {
		return Stream.of(in.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
	}

	private static int readInt() throws IOException {
		return Integer.parseInt(in.readLine());
	}

	private static long[] readLongs() throws IOException {
		return Stream.of(in.readLine().split(" ")).mapToLong(Long::parseLong).toArray();
	}

	private static long readLong() throws IOException {
		return Long.parseLong(in.readLine());
	}

	private static double[] readDoubles() throws IOException {
		return Stream.of(in.readLine().split(" ")).mapToDouble(Double::parseDouble).toArray();
	}

	private static double readDouble() throws IOException {
		return Double.parseDouble(in.readLine());
	}

	private static String readString() throws IOException {
		return in.readLine();
	}

	private static int setBit(int S, int j) {
		return S | (1 << j);
	}

	private static int isOn(int S, int j) {
		return S & (1 << j);
	}

	private static int clearBit(int S, int j) {
		return S & ~(1 << j);
	}

	private static int toggleBit(int S, int j) {
		return S ^ (1 << j);
	}

	private static int lowBit(int S) {
		return S & (-S);
	}

	private static int setAll(int n) {
		return (1 << n) - 1;
	}

	private static int modulo(int S, int N) {
		return ((S) & (N - 1));
	} // returns S % N, where N is a power of 2

	private static boolean isPowerOfTwo(int S) {
		return (S & (S - 1)) == 0 ? true : false;
	}

	private static int nearestPowerOfTwo(int S) {
		return ((int) Math.pow(2.0, (int) ((Math.log((double) S) / Math.log(2.0)) + 0.5)));
	}

	private static int turnOffLastBit(int S) {
		return ((S) & (S - 1));
	}

	private static int turnOnLastZero(int S) {
		return ((S) | (S + 1));
	}

	private static int turnOffLastConsecutiveBits(int S) {
		return ((S) & (S + 1));
	}

	private static int turnOnLastConsecutiveZeroes(int S) {
		return ((S) | (S - 1));
	}

	private static void open() {
		in = new BufferedReader(new InputStreamReader(System.in));
		out = new BufferedWriter(new OutputStreamWriter((System.out)));
	}

	private static void close() throws IOException {
		out.flush();
		out.close();
		in.close();
	}
}