standback, 45 bytes

Result

AC

Duration

819ms

Code [DL]

g/([^T]{50})./%1T/w/K /s/K /KK//m/^/S//%%'///

stdin

                                              T   
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
              K                                   

stdout

                                              T   
                                              T   
                                              T   
                                              T   
                                              T   
                                              T   
                                              T   
                                              T   
                                              T   
                                              T   
                                              T   
                                              T   
                                              T   
                                              T   
              KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKT   

stderr

strace