DB<1>  @elements = qw/ 1 3 5 4 6/;

  DB<2> $hash1{$_}++ for @elements;

  DB<3> x \%hash1
0  HASH(0x600509af0)
   1 => 1
   3 => 1
   4 => 1
   5 => 1
   6 => 1