#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11165436
use warnings;
use JSON::PP;

sub names
  {
  my ($data) = @_;
  if( 'ARRAY' eq ref $data )
    {
    map names($_), @$data;
    }
  elsif( 'HASH' eq ref $data )
    {
    map { my $id = $_; map "$id.$_", names($data->{$_}) } keys %$data;
    }
  else { "\n" }
  }

@ARGV or @ARGV = 'd.11165436.json';                   # FIXME filename
print map s/\.$//r, names decode_json join '', <>;