// URL: https://yukicoder.me/problems/no/813

import std.algorithm, std.container, std.math, std.range, std.typecons, std.string;

version(unittest) {} else
void main()
{
  int n; io.getV(n);
  double p, q; io.getV(p, q);

  auto a1 = new double[](n), a2 = new double[](n);
  a1[] = 0; a1[0] = 1; a2[] = 0;
  auto ao = 0.0L, ai = 0.0L, ad = 0.0L;

  auto b1 = new double[](n), b2 = new double[](n);
  foreach (i; 0..10^^4) {
    foreach (j; 0..n) {
      if (j > 0)
        b1[j] = a1[j-1]*q + a2[j-1]*p;
      if (j < n-1)
        b2[j] = a1[j+1]*p + a2[j+1]*q;
      b1[0] = 0;
      b2[n-1] = 0;
    }
    auto bo = ao + a1[0]*p + a2[0]*q;
    auto bi = ai + a1[n-1]*q;
    auto bd = 0.0L;
    foreach (j; 0..n) bd += a1[j] + a2[j];
    bd *= 1-p-q;

    a1[] = b1[]; a2[] = b2[];
    ao = bo; ai = bi; ad = bd;
  }

  io.put(ao);
}

auto io = IO();

struct IO
{
  import std.algorithm, std.conv, std.format, std.meta, std.range, std.stdio, std.traits;

  dchar[] buf;
  auto sp = (new dchar[](0)).splitter;
  int precision = 10;
  string delimiter = " ";

  void nextLine()
  {
    stdin.readln(buf);
    sp = buf.splitter;
  }

  auto get(T)(ref T v)
  {
    if (sp.empty) nextLine();
    v = sp.front.to!T;
    sp.popFront();
  }

  auto getV(T...)(ref T v)
  {
    foreach (ref w; v) get(w);
  }

  auto getA(T)(size_t n, ref T v)
  if (hasAssignableElements!T)
  {
    v = new T(n);
    foreach (ref w; v) get(w);
  }

  auto getC(T...)(size_t n, ref T v)
  if (allSatisfy!(hasAssignableElements, T))
  {
    foreach (ref w; v)
      w = new typeof(w)(n);
    foreach (i; 0..n)
      foreach (ref w; v) get(w[i]);
  }

  auto getM(T)(size_t r, size_t c, ref T v)
  if (hasAssignableElements!T && hasAssignableElements!(ElementType!T))
  {
    v = new T(r);
    foreach (ref w; v) getA(c, w);
  }

  auto rangePop(R)(ref R r)
  {
    r.popFront();
    if (!r.empty) write(delimiter);
  }

  auto putA(T)(T v)
  {
    static if (isInputRange!T && !isSomeString!T)
      for (auto w = v; !w.empty; rangePop(w)) putA(w.front);
    else if (isFloatingPoint!T)
      writef(format("%%.%df", precision), v);
    else
      write(v);
  }

  auto put(T...)(T v)
  {
    foreach (i, w; v) {
      putA(w);
      if (i < v.length-1) write(delimiter);
    }
    writeln;
  }

  auto putB(S, T)(bool c, S t, T f)
  {
    if (c)
      put(t);
    else
      put(f);
  }

  auto dbg(T...)(T v)
  {
    stderr.writeln(v);
  }
}