In this task, you are given two sets, and you need to count the number of elements at the intersection of two given sets.  A Set is shown by two curly braces and comma-separated numbers inside, like {1, 2, 3}. The intersection of two given sets is the largest set which contains all the elements that are common to both sets. To find the intersection of two given sets, A and B is a set consisting of all the elements common to both A and B.
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Question: Set1: '{20}', Set2: '{4, 5, 10, 13, 16, 18}'. How many elements are there in the intersection of Set1 and Set2 ?

Answer: 0


Question: Set1: '{3, 20, 13}', Set2: '{19, 12, 7}'. How many elements are there in the intersection of Set1 and Set2 ?

Answer: 0


Question: Set1: '{3, 4, 7, 8, 11, 14, 15, 17, 19}', Set2: '{3, 5, 7, 11, 12, 17, 18, 20}'. How many elements are there in the intersection of Set1 and Set2 ?

Answer:
4