<hppavilion[1]> learn zed is the 26th letter of the alphabet in Commonwealth English. Why they consider what is clearly a 3-letter string to be a single letter is unclear.

#!/usr/bin/perl
use Encode; binmode *$_,"encoding(utf8)" for STDIN,STDOUT; local$/; for (split//,<STDIN>) { rand(5)<3 and y/EOeo/\xc4\xc5\xe4\xe5/; print }