# 57*3 = 171
sub emb1 {
$_[0]=~/^(?{[("")x2]})(.*)(?{[$^R->[0].$1,$^R->[1]]})(?:(
.)(?{[$^R->[0],$^R->[1].$2]})(.*)(?{[$^R->[0].$3,$^R->[1]
]}))*\z(?(?{$^R->[0]eq$_[1]})(?{$_[2]=$^R->[1]})|(?!))/sx
}

# 54*3 = 162
sub emb2 {
our$i=\$_[2];@_=@_;my$R;$R=qr/(?{substr$_[1],0,1,''})(
(??{''ne$^R&&"[^\Q$^R\E]*\Q$^R"}))(?{chop($$i.=$1)if$1
ne'';$^R})(??{''ne$^R&&$R})(?{$$i.=$'})/x;$_[0]=~/^$R/
}

# 52*3 = 156
sub emb3 {
@_=(@_,our$i=\$_[2]);$_[0]=~m{^(?(?{${$^R=\substr$_[
1],0,1}ne''})((??{"[^\Q${$^R}\E]*\Q${$^R}"}))(?{chop
(${$^R},$$i.=$1)}))+(?(?{$_[1]ne''})^)}&&($$i.=$',1)
}

# 49*3 = 147
sub emb4 {
use re"eval";$_[0]=~m{^@{[map+qr{(?>([^$_]*)$_(?{
$_[$^F].=substr($_[$%],$-[-1],$+[$#-]-$-[-1])}))}
,map+quotemeta(),split//,$_[1]]}}x&&($_[2].=$',1)
}

# 41*3 = 123
sub emb5 {
$_[0]=~m{^@{[map"([^\Q$_\E]*)\Q$_",split/
/x,$_[1]]}}x&&($_[2]=join('',map(substr($
_[0],$-[$_],$+[$_]-$-[$_]),1..$#-),$'),1)
}