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.

Example Input: Set1: '{3, 6, 7, 10, 11, 16, 17, 18, 19, 20}', Set2: '{16, 19}'. How many elements are there in the intersection of Set1 and Set2 ?
Example Output: 2

Example Input: Set1: '{1, 4, 7, 9, 10, 11, 18, 20}', Set2: '{9, 11, 12}'. How many elements are there in the intersection of Set1 and Set2 ?
Example Output: 2

Example Input: Set1: '{1, 2, 9, 10, 17, 18}', Set2: '{18, 2, 10, 19}'. How many elements are there in the intersection of Set1 and Set2 ?
Example Output:
3