use warnings;
use strict;

foreach my $str ( 'LLLLLLLLLLLLLLLLLLLOOOOOOOOOOOOO', 'LLLLLLLLLLCOOOOOOOOOOOOOOOOOOOOOO' ){
    if($str=~/^(L+)/ or $str=~/^(L+C)/) {
        print "matched '$1'\n";
    }
}
__END__
matched 'LLLLLLLLLLLLLLLLLLL'
matched 'LLLLLLLLLL'