sub r
{
my ($f, $c) = @_;
return sub { print $c; $f->(); };
}
$r = sub {};
while (read STDIN, $_, 1) {
$w = /^[a-zA-Z]$/;
$n++ if ($w && !$l);
$l = $w;
if ($n & 1 || !$w) {
$r->(); $r = sub{};
print;
} else {
$r = r($r, $_);
$r->();