local n = io.read("*n")
local p, q = io.read("*n", "*n")

r, l = {}, {}
for i = 0, n+1 do
  r[i], l[i] = 0, 0
end
r[1] = 1

local rem = 1
local genten = r[1] * p
local migi = 0
local sinda = 0

local s, t = {}, {}
s[0] = 0
t[0] = 0
s[n+1] = 0
t[n+1] = 0

local tgt_r, tgt_l, prv_r, prv_l = s, t, r, l
while(0.001 <= rem) do
  for i = 1, n do
    tgt_r[i] = prv_r[i - 1] * q + prv_l[i - 1] * p
    tgt_l[i] = prv_l[i + 1] * q + prv_r[i + 1] * p
    sinda = sinda + (prv_r[i] + prv_l[i]) * (1 - p - q)
  end
  genten = genten + prv_l[1] * q
  migi = migi + prv_r[n] * q
  rem = 1 - sinda - genten - migi

  if(tgt_r == s) then
    tgt_r, tgt_l, prv_r, prv_l = r, l, s, t
  else
    tgt_r, tgt_l, prv_r, prv_l = s, t, r, l
  end
end
print(genten)