calc, 96 bytes

Result

AC

Duration

2024ms

Code [DL]

=REPT(LEFT(A1;51);B2/51)&REPT(C3;C2)&REPT(B3;FIND(A3;A1)-C2),=LEN(A1)-51,=FIND(B3;A1)-B2-1
T,K, 

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                     
KKKKKKKKKKKKKKKKKKKKKKKKKKKKK

stderr

javaldx: Could not find a Java Runtime Environment!
Warning: failed to read path from javaldx
convert /tmp/code.csv -> /tmp/out/code.csv using filter : Text - txt - csv (StarCalc)

strace