let input = stdin.ReadLine().Split(' ')
let N = input.[0] |> int
let p = input.[1] |> float

let p2 = 1.0 - p

let s = [| for i = 0 to N+1 do yield 1.0 |]
let mutable ans = 0.0
for i = 2 to N do
    ans <- ans + s.[i]
    for j in i*2 .. i .. N do
        s.[j] <- s.[j] * p2

printfn "%f" ans