while (<>) { push @input, lc =~ /[a-z]/g; while ( @input > 1 ) { my ($let1,$let2) = splice @input,0,2; if ($let2 eq $let1) { unshift @input, $let2; $let2 = ($let2 eq 'x') ? 'z': 'x'; } push @output, transcribe ($let1,$let2); } } if (@input) { push @output, transcribe ($input[0],($input[0] eq 'x') ? 'z': 'x'); }