in reply to Perl Golf-- testing array intersection

thundergnat relies on @x neither having '0' nor '' elements.

I think I can do better: 33 in scalar context, else 35: 

sub martin {
  #          1         2         3
  # 12345678901234567890123456789012345
    @z{@y}=(1)x@y;0+grep$_,delete@z{@x}
}

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