my %hash = ();

while( <DATA> ) {
   my( $lname, $fname, $score ) = split;
   $hash{$lname}{$fname} = $score;
}

#just last names
print join "\n", keys %hash;

print "\n---\n";

#names and scores:
for my $lname ( keys %hash ) {
	for my $fname ( keys %{ $hash{$lname} } ) {
		printf "$lname, $fname:  $hash{$lname}{$fname}\n"
	}
}

__DATA__
Lateur Bart 97
Pierce Jerrad 96
Unknown planetscape 101
Miller Katie 86