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.

Q: Set1: '{2, 5, 7}', Set2: '{1, 4, 7, 10, 17, 18}'. How many elements are there in the intersection of Set1 and Set2 ?

A: 1
****
Q: Set1: '{1, 2, 3, 5, 7, 12, 13, 17}', Set2: '{16, 11, 20, 13}'. How many elements are there in the intersection of Set1 and Set2 ?

A: 1
****
Q: Set1: '{6, 14, 15, 16, 18}', Set2: '{1, 2, 6, 12, 13, 15, 16}'. How many elements are there in the intersection of Set1 and Set2 ?

A:
3
****