UTAK QYK UTYU SGGE RWESIAPU LGIAQ VDGI AJBADOAPLA, YPE AJBADOAPLA, HAXX UTYU LGIAQ VDGI ZYE RWESIAPU.

##</code><code>##

perl -ne "print if m/^..(.)\1$/;" Words.knu

##</code><code>##

@ECHO OFF
perl -ne "print if m/^%1$/;" Words.knu

##</code><code>##

perl -ne "print if m/^[a-z][a-z]([a-z])\1$/;" Words.knu

##</code><code>##

perl -ne "print if m/^([a-z])(?!\1)([a-z])(?!\1)(?!\2)([a-z])\1$/;" Words.knu

##</code><code>##

([a-z])
(?!\1)([a-z])
##</code><code>##

([a-z])
(?!\1)([a-z])
(?!\1)(?!\2)([a-z])
##</code><code>##

([a-z])
(?!\1)([a-z])
(?!\1)(?!\2)([a-z])
(?!\1)(?!\2)(?!\3)([a-z])
##</code><code>##

([a-z])
(?!\1)([a-z])
(?!\1)(?!\2)([a-z])
(?!\1)(?!\2)(?!\3)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)([a-z])
##</code><code>##

([a-z])
(?!\1)([a-z])
(?!\1)(?!\2)([a-z])
(?!\1)(?!\2)(?!\3)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)(?!\5)([a-z])
##</code><code>##

([a-z])
(?!\1)([a-z])
(?!\1)(?!\2)([a-z])
(?!\1)(?!\2)(?!\3)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)(?!\5)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)(?!\5)(?!\6)([a-z])
##</code><code>##

([a-z])
(?!\1)([a-z])
(?!\1)(?!\2)([a-z])
(?!\1)(?!\2)(?!\3)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)(?!\5)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)(?!\5)(?!\6)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)(?!\5)(?!\6)(?!\7)([a-z])
##</code><code>##

([a-z])
(?!\1)([a-z])
(?!\1)(?!\2)([a-z])
(?!\1)(?!\2)(?!\3)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)(?!\5)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)(?!\5)(?!\6)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)(?!\5)(?!\6)(?!\7)([a-z])
(?!\1)(?!\2)(?!\3)(?!\4)(?!\5)(?!\6)(?!\7)(?!\8)([a-z])
##</code><code>##

perl -ne "print if m/^(.)..\1..\1..\1$/;" Words.knu

##</code><code>##

perl -ne "print if m/^..d..ent$/;" Words.knu