Task: Program Execution
Input (English): Set1: '{1, 2, 3, 4, 6, 13, 14, 16, 19, 20}', Set2: '{1, 3, 4, 5, 9, 12, 16, 18, 19}'. How many elements are there in the union of Set1 and Set2 ?
Output (English): 14