#include #include int main(int argc, string argv[]) { int key = argv[1]; //if (argc != 2) printf("%i\n", key); } /* Your program must accept a single command-line argument, a non-negative integer. Let’s call it *k* for the sake of discussion. If your program is executed without any command-line arguments or with more than one command-line argument, your program should print an error message of your choice (with printf) and return from main a value of 1 (which tends to signify an error) immediately. If any of the characters of the command-line argument is not a decimal digit, your program should print the message Usage: ./caesar key and return from main a value of 1. Do not assume that k will be less than or equal to 26. Your program should work for all non-negative integral values of k less than 2^31-26. In other words, you don’t need to worry if your program eventually breaks if the user chooses a value for k that’s too big or almost too big to fit in an int. (Recall that an int can overflow.) But, even if k is greater than 26, alphabetical characters in your program’s input should remain alphabetical characters in your program’s output. For instance, if k is 27, A should not become \ even though \ is positions away from A in ASCII, per asciitable.com; A should become B, since B is 27 positions away from A, provided you wrap around from Z to A. Your program must output plaintext: (with two spaces but without a newline) and then prompt the user for a string of plaintext (using get_string). Your program must output ciphertext: (with one space but without a newline) followed by the plaintext’s corresponding ciphertext, with each alphabetical character in the plaintext “rotated” by k positions; non-alphabetical characters should be outputted unchanged. Your program must preserve case: capitalized letters, though rotated, must remain capitalized letters; lowercase letters, though rotated, must remain lowercase letters. After outputting ciphertext, you should print a newline. Your program should then exit by returning 0 from main. */