Problem Statement 
 You will be given an equation of the form <side>=<side> where <side> is a list of <term>s separated by <op>s. Each <op> is either + or , and each <term> is a positive length string of uppercase letters. Each letter denotes a variable taking on real values. No letter will occur in a <term> more than twice.
The <term>s are products of variables. As you would expect, the + and  operators take lower precedence than the multiplications within the <term>s. For example, ABC+ADF=PQPQ
is a properly formatted equation. Sometimes, by fixing a single variable at a particular value, we can force the entire equation to always be true. Return a String[] containing all such variables that satisfy this requirement. If a variable can be set to n distinct values all of which satisfy this requirement, then that variable should occur n times in the return. If a variable can be set to an infinite number of distinct values that satisfy this requirement, it should not be returned. The return should be sorted in alphabetical order. 

Definition 
 Class:  VariableSolve  Method:  getSolutions  Parameters:  String  Returns:  String[]  Method signature:  String[] getSolutions(String equation)  (be sure your method is public) 




Constraints 
  equation will contain between 3 and 50 characters inclusive. 
  equation will be formatted as described in the problem statement. 

Examples 
0)  
  Returns: {"N", "P" }  Simpler than it looks: let N = 1 or P = 0. 


1)  
  Returns: {"E" }  Only E = 0 guarantees the equation holds. 


2)  
  Returns: { }  Each variable has an infinite number of values causing the equation to hold. 


3)  
  Returns: {"B" }  We cannot consider the complex solutions for A. 


4)  
 