package contest180803;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class D {
	InputStream is;
	PrintWriter out;
	String INPUT = "";
	
	// (x, y)
	// (x-a)^2+y^2=(a+y)^2
	// (x-b)^2+y^2=(b-y)^2
	public static double[] circumcircle(double[] a, double[] b, double[] c)
	{
		double ax = a[0], ay = a[1];
		double bx = b[0], by = b[1];
		double cx = c[0], cy = c[1];
		if((bx-ax)*(cy-ay)-(by-ay)*(cx-ax) == 0)return null; // 0はなまぬるいかも
		double D = 2*(ax*(by-cy)+bx*(cy-ay)+cx*(ay-by));
		double X = ((ax*ax+ay*ay)*(by-cy)+(bx*bx+by*by)*(cy-ay)+(cx*cx+cy*cy)*(ay-by))/D;
		double Y = ((ax*ax+ay*ay)*(cx-bx)+(bx*bx+by*by)*(ax-cx)+(cx*cx+cy*cy)*(bx-ax))/D;
		double R = Math.sqrt((X-ax)*(X-ax)+(Y-ay)*(Y-ay));
		return new double[]{X, Y, R};
	}
	
	double[] inv(double[] a)
	{
		double d = Math.sqrt(a[0]*a[0]+a[1]*a[1]);
		a[0] = -a[0]/d/d;
		a[1] = -a[1]/d/d;
		return a;
	}

	
	void solve()
	{
		int n = ni(), a = ni(), b = ni();
		double A = -1.0/(2*a);
		double B = -1.0/(2*b);
		double x = (A+B)/2;
		double y = (n-1)*(B-A)/2;
		
		double[] c0 = new double[]{x, y+(B-A)/2};
		double[] c1 = new double[]{B, y};
		double[] c2 = new double[]{A, y};
		
		double[] res = circumcircle(inv(c0), inv(c1), inv(c2));
		out.printf("%.14f\n", res[2]);
	}
	
	void run() throws Exception
	{
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//		Thread t = new Thread(null, null, "~", Runtime.getRuntime().maxMemory()){
//			@Override
//			public void run() {
//				long s = System.currentTimeMillis();
//				solve();
//				out.flush();
//				if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//			}
//		};
//		t.start();
//		t.join();
	}
	
	public static void main(String[] args) throws Exception { new D().run(); }
	
	private byte[] inbuf = new byte[1024];
	public int lenbuf = 0, ptrbuf = 0;
	
	private int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private long[] nal(int n)
	{
		long[] a = new long[n];
		for(int i = 0;i < n;i++)a[i] = nl();
		return a;
	}
	
	private char[][] nm(int n, int m) {
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private int[][] nmi(int n, int m) {
		int[][] map = new int[n][];
		for(int i = 0;i < n;i++)map[i] = na(m);
		return map;
	}
	
	private int ni() { return (int)nl(); }
	
	private long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); }
}