#usr/bin/perl!
use strict;
#I opened all files (containg the tables) one by one; is #there a way I can open all files at once?
open(FILEH1, "<table1.txt");
 while (my $file = <FILEH1>){
      chomp $file;
      my @file1 = split('\t', $file); #to pick IDs and #values => $file1[0] and $file1[1]
}

open(FILEH2, "<table2.txt");
#and continued to tables 3 and 4.

#And then I tried to collect the items which is where I got #stuck.