rust, 148 bytes

Result

AC

Duration

2249ms

Code [DL]

use std::io::*;fn main(){let mut a=[0;999];stdin().read(&mut a);let mut i=51;while a[i-1]<117{a[i]|=a[i-51]|a[i-1]&1;i+=1}stdout().write(&a[0..i]);}

stdin

                                        T         
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                               K                  

stdout

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

stderr

warning: unused `std::result::Result` that must be used
 --> /tmp/code.rs:1:44
  |
1 | use std::io::*;fn main(){let mut a=[0;999];stdin().read(&mut a);let mut i=51;while a[i-1]<117{a[i]|=a[i-51]|a[i-1]&1;i+=1}stdout().write(&a[0..i]);}
  |                                            ^^^^^^^^^^^^^^^^^^^^^
  |
  = note: #[warn(unused_must_use)] on by default
  = note: this `Result` may be an `Err` variant, which should be handled

warning: unused `std::result::Result` that must be used
 --> /tmp/code.rs:1:123
  |
1 | use std::io::*;fn main(){let mut a=[0;999];stdin().read(&mut a);let mut i=51;while a[i-1]<117{a[i]|=a[i-51]|a[i-1]&1;i+=1}stdout().write(&a[0..i]);}
  |                                                                                                                           ^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: this `Result` may be an `Err` variant, which should be handled

strace