use strict; # Please use these 2 pragmas
use warnings;

use autodie; #this one comes handy as well

if (@ARGV !=4 ) {
	die "Ooops etc..";
}

	# a more descriptive name for your vars, otherwise you may as well
	# use $ARV[0], $ARGV[1] etc...
my ($milcar_filename, $check_file, $matches_file, $three_column_file) = @ARGV;

#use the 3 args version of open;
open my $fh, '<', $milcar_filename; 
				#prg will 'die' if file error due to the autodie pragma
	
	#store some values into a hash	
my %hash;		
while my $line(<$fh>) {
	chomp $line;

		# I assume here that the milcar file is pipe separated
		# but replace the separator with the separaor of your choice
	my ($last_name, $first_name, $integer1, $word1,
			$integer2, $word2, $real_number) = split /\|/, $line;

		#build a key, see if the key already exists, and
		# update with the latest int2 value, if larger.
	my $key = $last_name . '_' . $first_name;
	if (exists $hash{$key} ) {

	   	if ($integer2 > $hash{key} ) {
			$hash{$key} = $integer2;
		}
	}
	else {
		$hash{$key} = $integer2;
	}
}