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.

Q: Set1: '{10, 19}', Set2: '{9, 18, 5, 7}'. How many elements are there in the union of Set1 and Set2 ?

A: 6
****
Q: Set1: '{1, 3, 6, 7, 8, 10, 11}', Set2: '{2, 3, 6, 9, 14, 18, 19}'. How many elements are there in the union of Set1 and Set2 ?

A: 12
****
Q: Set1: '{5, 10, 15, 17, 19, 20}', Set2: '{1, 2, 3, 6, 9, 10, 13, 14, 20}'. How many elements are there in the union of Set1 and Set2 ?

A:
13
****