node, 96 bytes

Result

AC

Duration

915ms

Code [DL]

a=require("fs").readFileSync(0);for(i=51;a[i-1]!=117;)a[i]|=a[i-51]|a[i++-1]&1;console.log(""+a)

stdin

                           T                      
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
        K                                         

stdout

                           T                      
                           t                      
                           t                      
                           t                      
                           t                      
                           t                      
                           t                      
                           t                      
                           t                      
                           t                      
                           t                      
        k!!!!!!!!!!!!!!!!!!u                      

stderr

strace