use strict;
use warnings;

use utf8;
use Encode qw/encode decode decode_utf8 encode_utf8 from_to/;


my $instr = decode('utf8', <STDIN>);

if($instr =~ /(.*)[Cc](.*)[Hh](.*)[Ii](.*)[Ww](.*)[Aa](.*)[Ww](.*)[Aa](.*)/ ) {
	my $str = "$1$2$3$4$5$6$7$8";
	print length($str);
} else {
	print -1;
}