Help required on XSL

I have an input XML in the form
<root>
<org>
<level>4</level>
<name></name>
</org>
<org>
<level>3</level>
<name></name>
</org>
<org>
<level>1</level>
<name></name>
</org>
<org>
<level>1</level>
<name></name>
</org>
<org>
<level>2</level>
<name></name>
</org>
<org>
<level>1</level>
<name></name>
</org>
<org>
<level>1</level>
<name></name>
</org>
<org>
<level>2</level>
<name></name>
</org>
<org>
<level>1</level>
<name></name>
</org>
<org>
<level>1</level>
<name></name>
</org>
</root>

Would like to convert the same to a hierarchical form based on <level> tag as
<level4>
<name></name>
<level3>
<name></name>
<level1>
<name></name>
</level1>
<level1>
<name></name>
</level1>
<level2>
<name></name>
<level1>
<name></name>
</level1>
<level1>
<name></name>
</level1>
</level2>
<level2>
<name></name>
<level1>
<name></name>
</level1>
<level1>
<name></name>
</level1>
</level2>
</level3>
</level4>

Can anyone help please with the XSL?

Hi JS

The definition of hierarchy in your sample is ambiguous.
What does 'level' mean?

If the first 'level 1' goes directly under 'level 3' Why the third 'level 1' goes under 'level 2' rather than under the same 'level 3'?