Inputs:
2
aab
aac
3
3
8
24

Output:
aab
c
INVALID


#!/usr/bin/perl

use strict;
use warnings;

$| = 1;     # flush output

# Get inputs
my $n = 0;        # number of strings
chomp( $n = <STDIN> );

my $i = 0;      # line counter
my $w = '';     # input string
my @S = ();     # uniq strings from inputs
while ( $i++ < $n )
{
    chomp ( $w = <STDIN> );
    push @S, get_uniq_strings( $w );
}

# Get the queries
my $q = 0;
chomp( $q = <STDIN> );

$i          = 0;
my $k       = '';
my @queries = ();
while ( $i++ < $q )
{
    chomp( $k = <STDIN> );
    push @queries, $k - 1;
}

# Output
@S = make_uniq( \@S );
my $uniq_len = scalar @S;
foreach ( @queries )
{
    print (( $_ <= $uniq_len ) ? "$S[ $_ ]\n" : "INVALID\n" );
}

exit;


sub get_uniq_strings
{
    my $string = shift;

    my @a = ();
    my $len = length $string;
    for ( my $i = 1; $i <= $len; $i++ )
    {
        for ( my $offset = 0; $offset < $len - $i + 1; $offset++ )
        {
            my $sub_str = substr $string, $offset, $i;
            push @a, $sub_str if $sub_str;
        }
    }

    @a;
}

sub make_uniq
{
    my $str_array = shift;

    my $uniq_array = {};
    foreach( @{ $str_array } )
    {
        $uniq_array->{ $_ }++ if $_;
    }

    sort keys %{ $uniq_array };
}