def qsort(l, fLess):
    if(len(l) < 2):
        return l
    pivot = l[0]
    l1 = filter(lambda x: fLess(x,l[0]), l[1:])
    l2 = filter(lambda x: not fLess(x,l[0]), l[1:])
    return qsort(l1,fLess)+[l[0]]+qsort(l2,fLess)