list comprehention

[Mathijs]

Hi,

Python beginner here and very much enjoying it. I'm looking for a 
pythonic way to find how many listmembers are also present in a reference 
list. Don't count duplicates (eg. if you already found a matching member 
in the ref list, you can't use the ref member anymore).

Example1: 
ref=[2, 2, 4, 1, 1]
list=[2, 3, 4, 5, 3]
solution: 2

Example2:
ref=[2, 2, 4, 1, 1]
list=[2, 2, 5, 2, 4]
solution: 3 (note that only the first two 2's count, the third 2 in the 
list should not be counted)

Any suggestions or comments?

Thanks.
M.


#my failing effort:
sum([min(r.count(n)-l[:i].count(n),l.count(n)) for i,n in enumerate(l)])

#test lists
import random
#reference list
r=[random.randint(1,5) for n in range(5)]
#list
l=[random.randint(1,5) for n in range(5)]