pius_dan.py

n = [10, 20, 20, 10, 10, 30, 50, 10, 20]
count = 0
for i in set(n):    # convert the list n to a set and loop over each value of the set
    # count inbuilt function to count the number of occurance of a value in an
    # list
    if n.count(i) // 2 >= 1:
        count += n.count(i) // 2
print(count)