import edu.neu.ccs.demeter.dj.*;
import java.util.*;

EquationSystem  = <equations> List(Equation).
List(S) ~ "(" {S} ")".
Equation = <lhs> Variable "=" <rhs> Expression.
Expression : Simple | Compound.
Simple : Variable | Numerical.
Variable = Ident.
Numerical = <v> int.
Compound = <op> Op List(Expression).
Op : Add.
Add = "+".
Main = .