HELLO_WORLD - Master process:
  A simple C++ program using MPI.

  The number of processes is 4

  Process 0 says 'Hello, world!'

HELLO_WORLD - Master process:
  Normal end of execution: 'Goodbye, world!'
  Process 1 says 'Hello, world!'
  Process 2 says 'Hello, world!'
  Process 3 says 'Hello, world!'