title: Infix to postfix for negative numbers
body: <p>How do I convert negative numbers from infix to postfix ?</p>
  
  <p>Suppose I have a expression</p>
  
  <p>a = - b - (-c-d) </p>
  
  <p>In some places I read that you can parathesize the negative numbers like </p>
  
  <p>a = (-b) - (-c-d)</p>
  
  <p>But here if I do that, I will get a term like "ab-" at the beginning of the postfix expression which means a-b and is incorrect.</p>
  
  <p>How do I convert this ?</p>