Hi Secode

If you need to get keys as output A B C you just use the below code. Always use Data::Dumper to see the complete stored hash format. I put the print statement in my code just refer that it will show the complete hash format. Your hash format is stored in this format

Your Hash stored format:
$VAR1 = {
          'A' => {
                   'B' => {}
                 }
        };
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This output is now stored..so, using this you can get the key output A
+ B C..so, assign some value for the key if you stored values in hash
$VAR1 = {
          'A' => {
                   'B' => {
                            'C' => 1
                          }
                 }
        };
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#!/usr/bin/perl

use Data::Dumper;

my %line;
$why = "";
$a = A;
$b = B;
$c = C;

$line{$a}{$b}{$c} = 1;
print Dumper(\%line);

$i = 1;

for $a (keys %line) {
for $b (keys %{$line{$a}}) {
for $c (keys %{$line{$a}{$b}}) {

print "$a $b $c\n";

}
}
}
<p>It prints output : A B C
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