import java.util.Map;
import java.util.TreeMap;

public class Plus extends BinaryExpression implements Expression{

    //constructor
    public Plus(Expression firstExp, Expression secondExp){
        super(firstExp, secondExp);
    }

    protected Expression getOperation(Expression first, Expression second) {
        return new Plus(first,second);
    }

    protected String getOperationString() {
        return "+";
    }

    protected double returnExp(double first, double second) {
        return first + second;
    }

    protected Expression getDifRules(Expression first, Expression second, Expression
            firstDx, Expression secondDx) {
        return new Plus(firstDx,secondDx);
    }


    public static void main(String args[]) throws Exception {
        Expression e2 = new Sin(new Var("x"));
        System.out.println(e2);
        System.out.println(e2.differentiate("x"));
        Expression e = new Div(new Num(1),new Var("y"));
        System.out.println(e);
        System.out.println(e.differentiate("y"));
    }
}