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 Python (3.4.3) (judge verdict: Wrong Answer)

nums = input().split(" ")
A = int(nums[0])
B = int(nums[1])

a1 = round((25*A)/2)
a2 = round((25*(A + 1))/2)

b1 = 10 * B
b2 = 10 * (B + 1)

length_a = a2 - a1
length_b = b2 - b1

if length_b == 0:
  print(-1)
else:
  if length_a == 0:
    xa = [a1]
  else:
    La = length_a + 1
    xa = [a1 + i for i in range(La)]
    if length_b == 1:
      xb = [b1]
    else:
      Lb = length_b
      xb = [b1 + i for i in range(Lb)] 
    conc = []
    for j in xa:
      for i in xb:
        if int(i) == int(j):
          conc.append(i)
    if conc == []:
      print(-1)
    else:
      print(min(conc))