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