import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		float numA = sc.nextFloat();
		float numB = sc.nextFloat()/5;
		float numC = sc.nextFloat();
		float numD = numA*numB;
		System.out.println(numD/numC);

	}
}