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
# -*- coding: utf-8 -*-
"""
http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=0094
"""
import sys


def sm_to_tsubo(a, b):
    return (a * b / 3.305785)



def main(args):
    for line in sys.stdin:
        a, b, = [int(x) for x in line.strip().split(' ')]
        result = sm_to_tsubo(a, b)
        print('{:.6f}'.format(result))

if __name__ == '__main__':
    main(sys.argv[1:])