1. Write a recursive function to calculate double factorial a, n!, where n is input by users. Please check slides for definition of double factorial 2. Assume a set {x: x is an even integer that>-0 and -32. Print out the number of its subsets. Moreover, print out the number of subsets that contain {2, 10, 24 You should let your C++ program to do the actual calculation. NOTE: For Problem 2, it is an application of product rule. Sample output: options compilation execution Problem 1 Please input an integer n: 6 double factorial is 48 Please input an integer n: 7 double factorial is 105 Problem 2 The set contains: 0246 8 10 12 14 16 18 20 22 24 26 28 30 32 The number of subsets is:XXXX The number of subsets containing (2, 10, 24) is Xxxx