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

local function getprimes(x)
  local primes = {}
  local allnums = {}
  for i = 1, x do allnums[i] = true end
  for i = 2, x do
    if(allnums[i]) then
      table.insert(primes, i)
      local lim = math.floor(x / i)
      for j = 2, lim do
        allnums[j * i] = false
      end
    end
  end
  return primes
end

local function getyakusuu(x, primes)
  local prime_num = #primes
  local tmp = {}
  local lim = math.ceil(math.sqrt(x))
  local primepos = 1
  local dv = primes[primepos]
  while(primepos <= prime_num and dv <= lim) do
    if(x % dv == 0) then
      tmp[dv] = 1
      x = x / dv
      while(x % dv == 0) do
        x = x / dv
        tmp[dv] = tmp[dv] + 1
      end
      lim = math.ceil(math.sqrt(x))
    end
    if(primepos == prime_num) then break end
    primepos = primepos + 1
    dv = primes[primepos]
  end
  if(x ~= 1) then tmp[x] = 1 end
  local cnt = 1
  for k, v in pairs(tmp) do
    cnt = cnt * (v + 1)
  end
  return cnt
end

local tot = 0
local primes = getprimes(n)
for i = 2, n do
  local z = getyakusuu(i, primes) - 2
  if(z == 0) then tot = tot + 1
  else tot = tot + (1 - p)^z end
end
print(string.format("%.8f", tot))