// A driver of circle

import java.text.DecimalFormat;
import java.util.Scanner;
class TestCircle1
{
	public static void main(String[] args)
	{
		DecimalFormat f2 = new DecimalFormat("0.00");
		Scanner input = new Scanner(System.in);
		Circle C0 = new Circle();
		double val = input.nextDouble();
		Circle SC = new Circle();
		SC.set(val);
		while(val>=0)
		{
			C0.set(val);
			System.out.println(f2.format(C0.area()));
			if(C0.smallerThan(SC))
				SC.set(val);	// NOTE: SC = C0 is wrong!

			val = input.nextDouble();
		}
		System.out.println("\n\nSmallest one: " + f2.format(SC.area()));

		System.out.println("\n\n\nDone.\n\n");
	}
}