import java.util.Scanner;

class Question379
{
	public static void main(String[] args)
	{
	
		Scanner scan = new Scanner(System.in);
		
		long yen = scan.nextLong();
		long gas = scan.nextLong();
		long v = scan.nextLong();
		
		long coin = yen / 5;
		long agas = coin * gas;
		double con = agas / v;
		
		System.out.println(con);

	}
}