fsharp-dotnet, 259 bytes

Result

AC

Duration

7309ms

Code [DL]

open System
let f=Console.ReadLine
let w (x:string)=Console.WriteLine x
let T=f()
let t=T.IndexOf 'T'
[<EntryPoint>]
let main v =
 w(T)
 let mutable i=f()
 while i.IndexOf 'K'<0 do
  w(T)
  i<-f()
 let k=i.IndexOf 'K'
 w(i.[..k]+String.replicate (t-k) "K")
 0

stdin

                T                                 
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
    K                                             

stdout

                T                                 
                T                                 
                T                                 
                T                                 
                T                                 
                T                                 
                T                                 
    KKKKKKKKKKKKK

stderr

The template "Console Application" was created successfully.

Processing post-creation actions...
Running 'dotnet restore' on /tmp/Proj/Proj.fsproj...
  Restoring packages for /tmp/Proj/Proj.fsproj...
  Generating MSBuild file /tmp/Proj/obj/Proj.fsproj.nuget.g.props.
  Generating MSBuild file /tmp/Proj/obj/Proj.fsproj.nuget.g.targets.
  Restore completed in 206.19 ms for /tmp/Proj/Proj.fsproj.

Restore succeeded.

strace