I can't tell what you want in $N, so here's some different things you can do:

@a = (3, 4, 5);

$N = @a[1..0];      # ===  $N = ();                   ===  $N = undef;
$N = @a[0..1];      # ===  $N = (3, 4);               ===  $N = 4;
$N = () = @a[0..1]; # ===  $N = num of ele in (3, 4)  ===  $N = 2;
$N = [ @a[0..1] ];  # ===  $N = [3, 4];               ===  $N = ARRAY(
+0x1abf0bc)
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You probably want to assign to an array:

@N = @a[0..1];      # ===  @N = (3, 4);
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