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
import java.math.*;
import java.util.*;
import static java.lang.System.*;

public class Main {
	//初期フィールド・メソッド---------------------------------------------
	static Scanner sc = new Scanner(System.in);
	static int min(int... ar) {Arrays.sort(ar); return ar[0];}
	static int max(int... ar) {Arrays.sort(ar); return ar[ar.length-1];}
	//------------------------------------------------------------


	//フィールド追加場所-----------------------------------------------
	//------------------------------------------------------------


	//メソッド追加場所------------------------------------------------
	//------------------------------------------------------------


	//mainメソッド---------------------------------------------------
	public static void main(String[] args) {
		int a = sc.nextInt();
		int b = sc.nextInt();
		BigDecimal bd1 = new BigDecimal(a*b);
		BigDecimal bd2 = new BigDecimal(3.305785);
		BigDecimal ans = bd1.divide(bd2,5,RoundingMode.HALF_UP);
		out.println(ans);
	}
	//------------------------------------------------------------
}
