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

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

rem = 1
genten = 0
migi = 0
sinda = 0
while(0.0001 <= rem) do
  s = {}
  t = {}
  s[0] = 0
  t[0] = 0
  for i = 1, n do
    s[i] = r[i - 1] * q + l[i - 1] * p
    t[i] = l[i + 1] * q + r[i + 1] * p
    sinda = sinda + (r[i] + l[i]) * (1 - p - q)
  end
  s[n+1] = 0
  t[n+1] = 0
  genten = genten + l[1] * q + r[1] * p
  migi = migi + r[n] * q
  rem = 1 - sinda - genten - migi
  for i = 0, n+1 do
    r[i] = s[i]
    l[i] = t[i]
  end
end
print(genten)