1. (10 points) a. At the beginning of C++ programs, we usually have the following two lines: #include using namespace std; Why do you need the first line? What is purpose of the second line? b. Can you still write a correct program without these two lines? If yes, please write a sample one below. c. What will be the output of the following program? Explain how you get it. #include using namespace std; int A =1; int fun(int &B, int C); int main() I/ line 1 / line 2 nt A-3, B-5; int&C-B; if (A 0) int B-5; C fun (A, B); cout