source_code: 
  
  import java.io.BufferedOutputStream;
  import java.io.BufferedReader;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.*;
  
  public class e {
  
  public static class FastReader {
  	BufferedReader br;
  	StringTokenizer st;
  	//it reads the data about the specified point and divide the data about it ,it is quite fast
  	//than using direct 
  
  	public FastReader() {
  		br = new BufferedReader(new InputStreamReader(System.in));
  	}
  
  	String next() {
  		while (st == null || !st.hasMoreTokens()) {
  			try {
  				st = new StringTokenizer(br.readLine());
  			} catch (Exception r) {
  				r.printStackTrace();
  			}
  		}
  		return st.nextToken();
  	}
  
  	int nextInt() {
  		return Integer.parseInt(next());//converts string to integer
  	}
  
  	double nextDouble() {
  		return Double.parseDouble(next());
  	}
  
  	long nextLong() {
  		return Long.parseLong(next());
  	}
  
  	String nextLine() {
  		String str = "";
  		try {
  			str = br.readLine();
  		} catch (Exception r) {
  			r.printStackTrace();
  		}
  		return str;
  	}
  }
  static ArrayList<String>list1=new ArrayList<String>();
  static void combine(String instr, StringBuffer outstr, int index,int k)
  {
  	if(outstr.length()==k)
  	{
  		list1.add(outstr.toString());return;
  	}
  	if(outstr.toString().length()==0)
  	outstr.append(instr.charAt(index));
      for (int i = 0; i < instr.length(); i++)
      {
          outstr.append(instr.charAt(i));
         
          combine(instr, outstr, i + 1,k);
          outstr.deleteCharAt(outstr.length() - 1);
      }
     index++;
  } 
  static ArrayList<ArrayList<Integer>>l=new ArrayList<>();
  static void comb(int n,int k,int ind,ArrayList<Integer>list)
  {
  	if(k==0)
  	{
  		l.add(new ArrayList<>(list));
  
  		return;
  	}
  	
  	
  	for(int i=ind;i<=n;i++)
  	{
  		list.add(i);
  		comb(n,k-1,ind+1,list);
  		
  		list.remove(list.size()-1);
  		
  	}
  	
  	
  	
  	
  	
  
  }
  
  
  public static PrintWriter out = new PrintWriter (new BufferedOutputStream(System.out));
  
  	public static void main(String[] args) {
  		// TODO Auto-generated method stub
  
  	FastReader in=new FastReader();
  	HashMap<Integer,Integer>map=new HashMap<Integer,Integer>();
  
  	int n=in.nextInt();
  	int r=in.nextInt();
  	 
  	double theta=(double)360/(double)n;
  	 
  	double b=1-((double)2/(double)(1-Math.cos((double)2*Math.PI/(double)n)));
  	double x=Math.sqrt(1-b)-1;
  	double ans=(double)r/(double)x;
  	System.out.println(ans);
  
  
  
  
  
  	}
  }
  