rust, 146 bytes

Result

WA

Duration

1699ms

Code [DL]

use std::io::*;fn main(){let mut a=[0;999];stdin().read(&mut a);let mut i=50;while a[i]<117{a[i+1]|=a[i-50]|a[i]&1;i+=1}stdout().write(&a[0..i]);}

stdin

                                  T               
                                                  
       K                                          

stdout

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

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=50;while a[i]<117{a[i+1]|=a[i-50]|a[i]&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:1:121
  |
1 | use std::io::*;fn main(){let mut a=[0;999];stdin().read(&mut a);let mut i=50;while a[i]<117{a[i+1]|=a[i-50]|a[i]&1;i+=1}stdout().write(&a[0..i]);}
  |                                                                                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: this `Result` may be an `Err` variant, which should be handled

strace