I have a folder which contains multiple files with this format :
[![enter image description here](https://i.stack.imgur.com/PWve9.png)](https://i.stack.imgur.com/PWve9.png)

I would like to rename all of these files so that I get :
391047.png, 416945.pdf, 416946.pdf, ..., 437703.png

I wish to do this with a batch cmd 

If someone could help me with this, I am really not familiar with batch commands ! 

Thank you in advance