sub p{my@x;map{my$c=$_;$_%$c||++$x[$_]for@_}@_=2..pop;grep$x[$_]==1,0..$#x}

##</code><code>##

sub p{@_=2..pop;my$c;while($_[$c]){@_=($_[$c],grep$_%$_[$c],@_);$c++}@_}

##</code><code>##

sub p{@_=2..pop;my$c;@_=($_[$c++],grep$_%$_[$c-1],@_)while$c<@_;@_}

##</code><code>##

sub p{grep{my$c=$_;$#_==grep$c%$_,@_}@_=2..pop}