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.

Set1: '{4, 9, 11, 13, 14, 15, 17, 18}', Set2: '{2, 10, 11, 16, 18}'. How many elements are there in the intersection of Set1 and Set2 ?
2

Set1: '{1, 3, 9, 12, 15, 17, 20}', Set2: '{16, 5, 13}'. How many elements are there in the intersection of Set1 and Set2 ?
0

Set1: '{1, 3, 10, 12, 15, 16, 18, 20}', Set2: '{9}'. How many elements are there in the intersection of Set1 and Set2 ?

0