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 Go (1.6) (judge verdict: Wrong Answer)

package main

import (
  "fmt"
)

func main() {
  var a,b float32
  fmt.Scan(&a,&b)
  result := -1
  var aRange [2] float32
  var bRange [2] float32
  aRange[0] = a/0.08
  aRange[1] = (a+1)/0.08
  bRange[0] = b/0.1
  bRange[1] = (b+1)/0.1
  a0 := int(aRange[0])
  a1 := int(aRange[1])
  b0 := int(bRange[0])
  b1 := int(bRange[1])
  for i := a0; i < a1; i++ {
    for j := b0; j < b1; j++ {
      if i == j{
        result = i
        break
      }
    }
    if result != -1{
        break
    }
  }
  if float32(result-1)*0.08 == a && float32(result-1)*0.1 == b{
    result -= 1
  }
  fmt.Println(result)
}