import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int c = scan.nextInt();
        int rin = scan.nextInt();
        int rout = scan.nextInt();
		double ans = 2 * 3.14 * 3.14 * rin * rin * rout;
        System.out.println(ans * c);
    }
}