standback, 43 bytes

Result

AC

Duration

854ms

Code [DL]

g/[^T]{50}\K./T/w/K /s/K /KK//m/^/S//%%'///

stdin

                    T                             
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
        K                                         

stdout

                    T                             
                    T                             
                    T                             
                    T                             
                    T                             
                    T                             
                    T                             
                    T                             
        KKKKKKKKKKKKT                             

stderr

strace