import random
def list_overlap(num_range, random_elements):
    a = random.sample(range(num_range), random.randint(0, random_elements))
    b = random.sample(range(num_range), random.randint(0, random_elements))
    c = []
    d = []
    result = []
    # to determine the longer list
    if len(a) > len(b):
        c = a
        d = b
    else:
        c = b
        d = a
    # to append the common elements
    for i in c:
        if i in d:
            result.append(i)
    print(result)


list_overlap(20, 15)