# use strict;
# use warnings;

chomp(my $S = <>);
my @r;
while ($S =~ /c.*?w.*?w/g) {
    push(@r, length(substr($S, $-[0], $+[0] - $-[0])));
}
print(scalar(@r) ? (sort({$a <=> $b} @r))[0] : -1, "\n");