Task: Program Execution
Input (English): Set1: '{1, 4, 6, 9, 10, 11, 12, 13, 14, 16}', Set2: '{4, 5, 7, 8, 10, 12, 16, 18, 19, 20}'. How many elements are there in the union of Set1 and Set2 ?
Output (English): 16