Perlの$&

ookawara@lx1:~$ cat a.pl
$s = "ABC";
$s =~ s/A//;
print "Match=$&\n";
$s = "BBC";
$s =~ s/A//;
print "Match=$&\n";
ookawara@lx1:~$ perl -f ./a.pl
Match=A
Match=Aそうなんだ・・・