$  perl -e 'my $s = "xyabcy*+!*+!*+!*+!*+!*+!"; $s =~ y/*+!//d; print $s, $/;'
xyabcy
$  perl -e 'my $s = "*+!xyabcy*+!*+!*+!*+!*+!*+!"; $s =~ y/*+!//d; print $s, $/;'
xyabcy
$