content: package v013;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.StringTokenizer;
  
  public class Graveryard_UVa1388 {
  	
  	static final double INF = 1e9;
  	
  	public static void main(String[] args) throws IOException {
  		
  		Scanner sc = new Scanner(System.in);
  		PrintWriter out = new PrintWriter(System.out);
  	
  		while(sc.ready())
  		{
  			int n = sc.nextInt(), m = sc.nextInt();
  			double d = 10000;
  			double[] pos = new double[n];
  			pos[0] = 0.0;
  			for(int i = 1; i < n; i++) pos[i] = pos[i-1] + d / n;
  			
  			double[] newPos = new double[n+m];
  			newPos[0] = 0.0;
  			for(int i = 1; i < n + m; i++) newPos[i] = newPos[i-1] + d / (n + m);
  			 
  			double min = 0;
  			for(int i = 0, j = 0; i < n; i++)
  			{
  				int idx = j;
  				while(j < n + m)
  				{
  					if(Math.abs(newPos[j] - pos[i]) < Math.abs(newPos[idx] - pos[i]))
  						idx = j;
  					else if(newPos[j] > pos[i])
  						break;
  					++j;
  				}
  				min += Math.abs(newPos[idx] - pos[i]);			
  			}
  			out.printf("%.4f\n", min);
  		}
  		out.flush();
  	}
  	
  	static class Scanner 
  	{
  		StringTokenizer st;
  		BufferedReader br;
  
  		public Scanner(InputStream s){	br = new BufferedReader(new InputStreamReader(s));}
  
  		public String next() throws IOException 
  		{
  			while (st == null || !st.hasMoreTokens()) 
  				st = new StringTokenizer(br.readLine());
  			return st.nextToken();
  		}
  
  		public int nextInt() throws IOException {return Integer.parseInt(next());}
  		
  		public long nextLong() throws IOException {return Long.parseLong(next());}
  
  		public String nextLine() throws IOException {return br.readLine();}
  		
  		public double nextDouble() throws IOException
  		{
  			String x = next();
  			StringBuilder sb = new StringBuilder("0");
  			double res = 0, f = 1;
  			boolean dec = false, neg = false;
  			int start = 0;
  			if(x.charAt(0) == '-')
  			{
  				neg = true;
  				start++;
  			}
  			for(int i = start; i < x.length(); i++)
  				if(x.charAt(i) == '.')
  				{
  					res = Integer.parseInt(sb.toString());
  					sb = new StringBuilder("0");
  					dec = true;
  				}
  				else
  				{
  					sb.append(x.charAt(i));
  					if(dec)
  						f *= 10;
  				}
  			res += Integer.parseInt(sb.toString()) / f;
  			return res * (neg?-1:1);
  		}
  		
  		public boolean ready() throws IOException {return br.ready();}
  
  
  	}
  }
  