open System

let readStringList () =
    let rec readLines acc =
        let line = Console.ReadLine()
        if String.IsNullOrEmpty(line) then
            List.rev acc
        else
            readLines (line :: acc)
    readLines []

let sortByLength strings =
    strings |> List.sortBy (fun s -> s.Length)

let printStringList strings =
    strings |> List.iter (fun s -> printfn "%s" s)

let demonstrateWithSample () =
    let sampleStrings = ["hello"; "world"; "a"; "programming"; "test"]
    printfn "Original list:"
    printStringList sampleStrings
    printfn "\nSorted by length:"
    let sorted = sortByLength sampleStrings
    printStringList sorted

[<EntryPoint>]
let main argv =
    printfn "Enter strings (empty line to finish):"
    let strings = readStringList ()
    
    if List.isEmpty strings then
        printfn "No strings entered. Using sample data:"
        demonstrateWithSample ()
    else
        printfn "\nOriginal strings:"
        printStringList strings
        
        printfn "\nSorted by length:"
        let sortedStrings = sortByLength strings
        printStringList sortedStrings
    
    0