Task: Program Execution
Input (English): Set1: '{2, 3, 4, 5, 7, 9, 12, 15, 17, 20}', Set2: '{1, 3, 5, 6, 11, 14, 16, 19, 20}'. How many elements are there in the union of Set1 and Set2 ?
Output (English): 16