In this task, you are given two sets, and you need to count the number of elements at the union of two given sets. A Set is shown by two curly braces and comma-separated numbers inside, like {1, 2, 3}. Union of two given sets is the smallest set which contains all the elements of both the sets. To find the union of two given sets, A and B is a set that consists of all the elements of A and all the elements of B such that no element is repeated.

Set1: '{16, 17, 19, 15}', Set2: '{3, 6}'. How many elements are there in the union of Set1 and Set2 ?
6

Set1: '{5}', Set2: '{3, 4, 5, 8, 10, 15, 16, 18, 19, 20}'. How many elements are there in the union of Set1 and Set2 ?
10

Set1: '{7, 12, 13, 14, 18}', Set2: '{9}'. How many elements are there in the union of Set1 and Set2 ?

6