png to pdf file

I have 406 .png images, and I want to put them in a .pdf.  Any suggestions on how to do that?  I can print one at a time and just save as a pdf, but I have 406 images.  So, that might too long. 

Or you could write a small shell script that generates the LaTeX code to embed all those images in one document. (\includegraphics, etc)