import java.math.BigDecimal;
import java.util.Scanner;

public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		while(sc.hasNext()){
			double n=sc.nextDouble(); n=n-n%5;
			double g=sc.nextDouble();
			double v=sc.nextDouble();
			BigDecimal nn=new BigDecimal(n);
			BigDecimal gg=new BigDecimal(g);
			BigDecimal vv=new BigDecimal(v);
			nn=nn.divide(BigDecimal.valueOf(5));
			nn=nn.multiply(gg);
			nn=nn.divide(vv,20,BigDecimal.ROUND_HALF_UP);
			System.out.println(nn.toPlainString());
		}
	}
}