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: Accepted)

# coding: utf-8

a, b = map(int, input().split())
# print(a,b)
# x=-1
# y=-1

# xr=[]
# yr=[]
# for i in range(1,101):
#     if i*0.08//1==a:
#         # print("x:{}".format(i))
#         x=i
#         xr.append(x)
# for i in range(1,101):
#     if i *0.1//1==b:
#         # print("y:{}".format(i))
#         y=i
#         yr.append(y)
# flag=False
#
# result=[]
# for i in xr:
#     for j in yr:
#         if i==j:
#             result.append(i)
#
# if len(result)>0:
#     print(result[0])
# else:
#     print('-1')
flag =False
for i in range(1,1010):
    if i*0.08//1==a and i*0.1//1==b:
        print(i)
        flag=True
        break

if not flag:
    print(-1)