Challenge 1: A Two-Line iostream Hello World — Possible Solution
====================================================================

#include <iostream>

int main() {
    std::cout << "Hello, C++!" << std::endl;
    std::cout << "This is a second line." << std::endl;
    return 0;
}

$ g++ hello.cpp -o hello
$ ./hello

Output:

    Hello, C++!
    This is a second line.

WHY THIS WORKS AS AN ANSWER
------------------------------
Two separate std::cout statements, each ending with std::endl (which
both flushes the stream and inserts a newline), and compiled with g++
rather than gcc -- following the chapter's own naming convention (.cpp
source file, g++ compiler) even though the underlying compile-then-link
model is otherwise identical to C.