Task: Program Execution
Input (English): Set1: '{2, 5, 7, 8, 10, 12, 13, 16, 17}', Set2: '{2, 3, 5, 11, 12, 14, 16, 17, 19, 20}'. How many elements are there in the union of Set1 and Set2 ?
Output (English): 14