Input : a = [1, 2, 3, 1, 2, 3] Output : 6 Count the number of entries in the list a. Input : a =  Output : 0
The idea is to use len() in Python
The length of list is: 4
The length of list is: 3
How does len() work?
len() works in O(1) time as list is an object and has a member to store its size. Below is description of len() from Python docs.
Return the length (the number of items) of an object. The argument may be a sequence (such as a string, bytes, tuple, list, or range) or a collection (such as a dictionary, set, or frozen set).
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