calc, 118 bytes

Result

AC

Duration

1958ms

Code [DL]

=REPT(LEFT(A1;51);B2-1)&REPT(C3;MOD(C2-1;51))&REPT(B3;MOD(1+D2-C2;51)),=(LEN(A1)+1)/51,=FIND(B3;A1),=FIND(A3;A1)
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      
                                           T      
                         KKKKKKKKKKKKKKKKKKK

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