Have you ever heard of the unit "○○ tsubo" that expresses the area of ​​land? Since ancient times, one samurai has said the area for making rice to eat in a day.

There is a land of a [m] x b [m]. Enter a and b and create a program that outputs the tsubo area S [tsubo] of the land. 1 tsubo = 3.305785 [m2], and a and b are integers less than or equal to 100.



input


a b


A and b separated by one space are given on one line.

output

Output the tsubo area S in one line. An error of 0.0001 or less is allowed.

Example

Input

15 25


Output

113.437508
#http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=0094
N = input().split()
a = N[0]
b = N[-1]
a = int(a)
b = int(b)
c = a * b
c = float(c)
d = c / 3.305785
print(d)