##
camel
perl
book
camel perl
perl book
camel perl book
####
sub list {
my $words=shift;
chomp $words;
my @words=split /\s/, $words;
my @longs=();
for my $i (1..$#words-1) {
push @longs, map { join " ", @words[$_..$_+$i]} (0..$#words-$i);
}
push @words, @longs,$words;
return @words;
}