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)

cmin = lambda a,b : a if a<b else b
cmax = lambda a,b : a if a>b else b
iin = lambda : int(input())
lin = lambda : list(map(int,input().split()))
rin = lambda n : [int(input()) for _ in range(n)]

a,b = map(int,input().split())

ia = a/(0.08)
la = int(ia*0.08)
while la==a:
    ia += 1
    la = int(int(ia)*0.08)
ia -= 1
lla =int(ia)

ia = a/(0.08)
la = int(ia*0.08)
while la==a:
    ia -= 1
    la = int(int(ia)*0.08)
ia = int(ia)+1

ib = b/(0.1)
lb = int(ib*0.1)
while lb==b:
    ib += 1
    lb = int(int(ib)*0.1)
ib -= 1
llb = int(ib)

ib = b/(0.1)
lb = int(ib*0.1)
while lb==b:
    ib -= 1
    lb = int(int(ib)*0.1)
ib = int(ib)+1

sa = set(range(ia,lla+1))
sb = set(range(ib,llb+1))
ans = sa & sb
print(min(ans) if ans else -1)