hello 
i think my request is a newbie one
i want to search pdf from a website and only pdf 
but i cannot settle the good configuration 
the link where pdf are located is :
draaf.nord-pas-de-calais.agriculture.gouv.fr/IMG/pdf/

i have settled the website as : draaf.nord-pas-de-calais.agriculture.gouv.fr/

i have put +*.pdf and -*.html 
but it seems to retrieve the whole website

can someone help me ? 

thank you
nicolas