#!/usr/bin/env perl                                                                                               

use strict;
use warnings;
use Set::Scalar;

my @account = qw( 96329XY 7776fc 334457yg 2233oop 000001 8877666b);

my @file = qw(8877666b.txt 2233oop.txt 334457yg.txt 7776fc.txt 96329XY_K.txt);

s/\.txt// for @file;

my $account_set = Set::Scalar->new(@account);

my $file_set = Set::Scalar->new(@file);

my $intersection = $account_set * $file_set;

$intersection->as_string_callback( sub { join qq(\n), sort $_[0]->elements } );

print qq($intersection\n);

__END__

karls-mac-mini:monks karl$ ./1102555.pl                                                                           
2233oop                                                                                                           
334457yg                                                                                                          
7776fc                                                                                                            
8877666b