open System

let workOf days = function
    | work when work>0 ->
        let w = float work
        let d = float days
        (w/pown d 2) |> floor |> int |> Some
    | _ ->
        None 

let rec workOfDue day work prev=
    let s=workOf day work
    match s with
    | None -> 
        prev
    | Some w ->
        workOfDue (day-1) (work-w) w

[<EntryPoint>]
let main argv = 
    let w = Console.ReadLine () |> int
    let d = Console.ReadLine () |> int
    workOfDue d w 0 |> printfn "%d"
    0