how to get value from array in array in array?

I get this array when I print_r($_POST), from the below result I want to get the value of skin.

[skin] => 1.jpg

how will i do that ???

 Array
    (
        [form_key] => WceDMPJOQD17ZeSW
        [config_state] => Array
            (
                [themeoptions_general] => 1
            )

        [groups] => Array
            (
                [general] => Array
                    (
                        [fields] => Array
                        开发者_开发百科    (
                                [themeoptions_images] => Array
                                    (
                                        [skin] => 1.jpg
                                    )

                                [themeoptions_customcss] => Array
                                    (
                                        [value] => color:#333;
                                    )

                            )

                )

        )

)

$_POST['groups']['general']['fields']['themeoptions_images']['skin']

This will give you the value of skin.

echo $_POST['groups']['general']['fields']['themeoptions_images']['skin']

prints

1.jpg