instruction:
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.
question:
Set1: '{1, 5, 8, 9, 10, 16, 18, 19, 20}', Set2: '{4, 5, 6, 11, 14, 18, 20}'. How many elements are there in the intersection of Set1 and Set2 ?
answer:
3


question:
Set1: '{10, 12}', Set2: '{17, 3, 5}'. How many elements are there in the intersection of Set1 and Set2 ?
answer:
0


question:
Set1: '{3, 5, 9, 13, 16, 19}', Set2: '{16, 10, 5, 14}'. How many elements are there in the intersection of Set1 and Set2 ?
answer:

2