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 v5.12) (judge verdict: Wrong Answer)

function Main(input) {
    var A = parseInt(input[0], 10);
    var B = parseInt(input[1], 10);
    
    var aMin = Math.ceil(A / 0.08);
    var aMax = (A+1) / 0.08 === Math.ceil((A+1) / 0.08) ? (A+1) / 0.08 - 1 : Math.floor((A+1) / 0.08);
    
    var bMin = Math.ceil(B / 0.1);
    var bMax = (B+1) / 0.08 === Math.ceil((B+1) / 0.08) ? (B+1) / 0.1 - 1 : Math.floor((B+1) / 0.1);

        console.log(aMin);
        console.log(aMax);
        console.log(bMin);
        console.log(bMax);
    if (aMin === bMin) {
        console.log(aMin);
    } else if (aMin > bMin) {
        if (bMax >= aMin) {
            console.log(aMin);
        } else {
            console.log(-1);
        }
    } else {
        if (aMax >= bMin) {
            console.log(bMin);
        } else {
            console.log(-1);
        }
    }
}

Main(require("fs").readFileSync("/dev/stdin", "utf8").trim().split(/\n|\s/));