use strict;
my $str = 'Thinh
Nguyen Thinh
Nguyen Ngoc Thinh
Nguyen A B C Thinh';
my $regex = qr`^(?:([\w]*)(?: (.*))? )?([\w]+)$`mp;
my $subst = '';
my $result = $str =~ s`$regex`$subst`rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html