use warnings;
use strict;

my %number = (
    23 => [['g1', 23, 24], ['g2', 34, 35]],
    24 => [['g3', 45, 56], ['g4', 36, 48]],
);

print "First group is: $number{23}[0][0]\n";

##</code><code>##

First group is: g1