awk, 111 bytes

Result

AC

Duration

791ms

Code [DL]

NR==1{sub("T(.+)","T");t=$0}NR>1{print t}END{sub("K(.+)","K");while(length($0)<length(t)){sub("K","KK")};print}

stdin

                                                 T
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                    K                             

stdout

                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                                                 T
                    KKKKKKKKKKKKKKKKKKKKKKKKKKKKKK

stderr

strace