#1.
def common(L1,L2):
    ans = []
    for x in L1:
        if x in L2:
            ans += [x]
    return ans

print common([1,5,4,3,2],[4,5,10,15])

#2.


def splitter(string,splitAt):
    ans = []
    counter = 
    
def alphabetize(names):
    ans = ""
    newnames = names.split(",")
    newnames = [
