#!/usr/bin/perl

use strict;
use warnings;

my %result;

for my $file ("File_A","File_B","File_C") {

    open (my $fh,"<",$file) or die "Can't open file $file: $!";
    <$fh>; # skip header line

    while (my $line = <$fh>) {
        my ($server,$cpua) = (split(",",$line))[0,1];
        push @{$result{$server}},$cpua;
    }

    close $fh or die "Can't close file $file: $!";
}

open (my $nfh,">","Result_File") or die "Can't open result file: $!";

for my $server (sort keys %result) {
    print $nfh $server.",".join(",",@{$result{$server}})."\n";
}
close $nfh or die "Can't close result file: $!";