title: How to detect overflow flag?
body: <p>In the following question, i wonder why OVERFLOW flag is set to 1.
  I know that overflow can only happen when adding two numbers of the same sign and
  getting a different sign.
  Is this is a mistake in the solution of the book or what?</p>
  
  <p><img src="https://i.stack.imgur.com/Q0Tev.jpg" alt="enter image description here"></p>