#!/usr/bin/env perl
use warnings;
use 5.12.0;

my $extra = 1;


print 'key enter: ';
my $c = <>;
chomp $c;

given ( $c ) {
    when ( 'a' ) {
        say 'a';
    }
    when ( 'b' ) {
        say 'c';
    }
    if ( $extra ) {
        when ( 'd' ) {
            say 'd';
        }
        when ( 'e' ) {
            say 'e';
        }
    }
    when ( 'z' ) {
        say 'z';
    }
    default {
        say 'something else';
    }
}