import java.util.Scanner;

public class Test {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		long n = sc.nextLong(), g = sc.nextLong(), v = sc.nextLong();
		long m = n / 5, a = m * g / v, b = (m * g) % v;
		System.out.print(a);
		if (b == 0) {
			return;
		}
		System.out.print(".");
		for (int i = 0; b > 0 && i < 12; i++) {
			System.out.print((b * 10) / v);
			b = (b * 10) % v;
		}
		System.out.println();
	}
}