Task: Program Execution
Input (English): Set1: '{1, 2, 6, 8, 9, 10, 11, 12, 17, 19}', Set2: '{4, 5, 6, 7, 10, 11, 12, 14, 18, 20}'. How many elements are there in the union of Set1 and Set2 ?
Output (English): 16