import java.util.Scanner;

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

	}
}