a. Write a function countDivisibleBy6() that takes as parameters two integers (nl and n2) and returns how many numbers are divisible by 6 between n1 and n2 (n2 should be greater than n1; if n2 is less than n1, the function returns -1). Write the prototype and the definition of the function. b. Write a C++ program that asks the user to enter two integers and uses the function countDivisibleBy6() to print on the screen how many numbers are divisible by 6 between nl and n2. Sample run: Please enter two integers: 1 32 4 numbers are divisible by 6 between 1 and 32