(Program
{-(Comparison
  {-(Identifier)-}
  {-(Identifier)-})-}
  (Equal
    (Identifier)
    (Identifier))
{+(Not
  {+(Equal
    {+(Identifier)+}
    {+(Identifier)+})+})+}
{+(Equal
  {+(Identifier)+}
  {+(Identifier)+})+}
{-(Assignment
  {-(Identifier)-}
  {-(Not
    {-(Identifier)-})-})-})