Not getting desire output by using switch statement in Perl

[rammohan]

#!/usr/bin/perl -w
use strict;
use warnings;
use feature "switch";

my$z = "d";
my($a,$b,$c,$d,$e) =  split(//, $z);
given($a eq "a" || "b"|| "c" || "d"|| "e"||"f" || "g"|| "h"||"i" ||"j"
+ || "k"|| "l"||"m" || "n"|| "o"||"p" || "q"|| "r"||"s" || "t"|| "u"||
+"v" || "w"|| "x"||"y" || "z"){
    when ('a'){ print "1";}
    when ('b'){print "2";}
    when ('c'){print "3";}
    when ('d'){print "4";}
    when ('e'){print "5";}
    when ('f'){print "6";} 
    when ('g'){print "7";}
    when ('h'){print "8";}
    when ('i'){print "9";}
    when ('j'){print "10";}
    when ('k'){print "11";}
    when ('l'){print "12";}
    when ('m'){print "13";}
    when ('n'){print "14";}
    when ('o'){print "15";}
    when ('p'){print "16";}
    when ('q'){print "17";}
    when ('r'){print "18";}
    when ('s'){print "19";} 
    when ('t'){print "20";}
    when ('u'){print "21";}
    when ('v'){print "22";}
    when ('w'){print "23";}
    when ('x'){print "24";}
    when ('y'){print "25";}
    when ('z'){print "26";}
default{print 'Everything else'}
}

When i executing this script i'm getting output only  2 . Please let us know.