#!/usr/local/bin/perl -w
use strict;
my (@list1, @list2, @list3, $c);


open(F1,"f1.lst");
open(F2,"f2.lst");
open(F3,"f3.lst");

# Populate the arrays

$c = 0;
while ( <F1> ) {
    next if ( $c == 0 ) and $c++;  # skip the file header
    chomp;
    $list1[$c++] = "$_ |" ;
};
close(F1);

$c = 0;
while ( <F2> ) {
    next if ( $c == 0 ) and $c++;  # skip the file header
    chomp;
    $list2[$c++] = "$_ |" ;
}
close(F2);

$c = 0;
while ( <F3> ) {
    next if ( $c == 0 ) and $c++;  # skip the file header
    chomp;
    $list3[$c++] = "$_ |" ;
}
close(F3);

I have no clue where to begin...