import java.util.Scanner;

public class ExactRegularPolygon {

	public static void main ( String [] args ) {

	BufferedReader input = new BufferedReader(new InputStreamReader(System.in);
	double n = 0d;
	double s = 0d, perimeter = 0d, r = 0d;
	double R = 0d;
	double circumare = 0d, inscrarea = 0d, area = 0d;
	String ni;

	System.out.println("\nHow many sides on this polygon?");
	ni = new String(input.readLine());
	n = Double.parseDouble(ni);
	
	System.out.println("\nAnd how long are the sides?");
	s = double.parseDouble(input.readLine());
	

	perimeter = n * s;
	R = s / (2 * (Math.sin(Math.PI/n)));
 
	System.out.println("\n"+R);

	}
}