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 JavaScript (Node.js 12.16.1) (judge verdict: Wrong Answer)

function *main() {
  
  const [A, B] = (yield).split(" ").map(s => +s);
  
  // floor(X/25) = A/2 => A*25/2 <= X <= A*25/2+24
  // floor(X/10) = A => A*10 <= X <= A*10+9
  const l1 = (A%2) ? Math.floor(A/2)*25+13 : Math.floor(A/2)*25, r1 = l1+24;
  const l2 = 10*B, r2 = l2+9;
  
  if (r1 < l2 || r2 < l1) {
    console.log(-1);
  } else {
    console.log(Math.max(l1, l2));
  }
  
}

const iter = main();
iter.next();
require("readline").createInterface({input: process.stdin}).on("line", s => iter.next(s));