Problem: NN is an experienced internet user and that means he spends a lot of time on the social media. Once he found the following image on the Net, which asked him to compare the sizes of inner circles:

<image>

It turned out that the circles are equal. NN was very surprised by this fact, so he decided to create a similar picture himself.

He managed to calculate the number of outer circles n and the radius of the inner circle r. NN thinks that, using this information, you can exactly determine the radius of the outer circles R so that the inner circle touches all of the outer ones externally and each pair of neighboring outer circles also touches each other. While NN tried very hard to guess the required radius, he didn't manage to do that. 

Help NN find the required radius for building the required picture.

Input

The first and the only line of the input file contains two numbers n and r (3 ≤ n ≤ 100, 1 ≤ r ≤ 100) — the number of the outer circles and the radius of the inner circle respectively.

Output

Output a single number R — the radius of the outer circle required for building the required picture. 

Your answer will be accepted if its relative or absolute error does not exceed 10^{-6}.

Formally, if your answer is a and the jury's answer is b. Your answer is accepted if and only when (|a-b|)/(max(1, |b|)) ≤ 10^{-6}.

Examples

Input

3 1


Output

6.4641016


Input

6 1


Output

1.0000000


Input

100 100


Output

3.2429391

Solution (in JAVA):

Solution:


import java.util.*;
import java.lang.*;
import java.lang.reflect.Array;
import java.io.*;
import java.util.HashMap;
import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStreamReader; 
import java.util.Scanner; 
import java.util.StringTokenizer; 
import java.io.DataInputStream; 
import java.io.FileInputStream; 
public class Prac {
    public static int min(int a,int b,int c){
        if(a<b){
            if(a<c)
                return a;
            
            else
                return c;
        }
        else{
            if(b<c)
                return b;
            else
                return c;
        }   
}
    public static int max(int a,int b,int c){
        if(a<b){
            if(b<c)
                return c;
            
            else
                return b;
        }
        else{
            if(a<c)
                return c;
            else
                return a;
        }   
}
    static class InputReader {
 
		private final InputStream stream;
		private final byte[] buf = new byte[8192];
		private int curChar, snumChars;
 
		public InputReader(InputStream st) {
			this.stream = st;
		}
 
		public int read() {
			if (snumChars == -1)
	 			throw new InputMismatchException();
			if (curChar >= snumChars) {
				curChar = 0;
				try {
					snumChars = stream.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (snumChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}
 
		public int ni() {
			int c = read();
			while (isSpaceChar(c)) {
				c = read();
			}
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}
 
		public long nl() {
			int c = read();
			while (isSpaceChar(c)) {
				c = read();
			}
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}
 
		public int[] nia(int n) {
			int a[] = new int[n];
			for (int i = 0; i < n; i++) {
				a[i] = ni();
			}
			return a;
		}
 
		public String rs() {
			int c = read();
			while (isSpaceChar(c)) {
				c = read();
			}
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}
 
		public String nextLine() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c));
			return res.toString();
		}
 
		public boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}
 
		private boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}
 
	}
    static abstract class MultiSetImpl<ValueType, MapType extends Map<ValueType, Integer>> implements MultiSet<ValueType> {
        protected final MapType map;
        protected int size;
        protected int distinctCount;

        protected MultiSetImpl(MapType map) {
            this.map = map;
            this.size = 0;
        }

        public void add(ValueType value) {
            int count = getCount(value);
            if (count == 0) ++distinctCount;
            map.put(value, count + 1);
            ++size;
        }

        public boolean remove(ValueType value) {
            int count = getCount(value);
            if (count == 0) return false;

            if (count == 1) map.remove(value);
            else map.put(value, count - 1);
            if (count == 1) --distinctCount;
            --size;
            return true;
        }

        public int getCount(ValueType value) {
            Integer count = map.get(value);
            return (count == null ? 0 : count);
        }

        @Override
        public String toString() {
            StringBuilder stringBuilder = new StringBuilder();
            for (ValueType key : map.keySet()) {
                stringBuilder.append("[" + key.toString() + " " + map.get(key).toString() + "] ");
            }
            return stringBuilder.toString();
        }

    }

    static interface MultiSet<ValueType> {
    }

    static class FastReader {
        private InputStream stream;
        private byte[] buf = new byte[8192];
        private int curChar;
        private int pnumChars;

        public FastReader(InputStream stream) {
            this.stream = stream;
        }

        private int pread() {
            if (pnumChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= pnumChars) {
                curChar = 0;
                try {
                    pnumChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (pnumChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = pread();
            while (isSpaceChar(c))
                c = pread();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = pread();
            }
            int res = 0;
            do {
                if (c == ',') {
                    c = pread();
                }
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = pread();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        private boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

    }

    static class HashMultiSet<ValueType> extends MultiSetImpl<ValueType, Map<ValueType, Integer>> {
        public HashMultiSet(Map<ValueType, Integer> map) {
            super(map);
        }

    }

    
    
    static PrintWriter w = new PrintWriter(System.out);
    
    public static void main(String[] args) throws IOException {
        InputReader sc=new InputReader(System.in);
        HashMultiSet<Integer> multiSet = new HashMultiSet<>(new HashMap<>());
        StringBuilder stringBuilder = new StringBuilder();
        

        
        double n=sc.ni();
        double r=sc.ni();
        double sin=Math.sin(Math.PI/n);
        double ans=(r*sin)/(1-sin);
        w.println(ans);
       w.close();
    }  
}