public static void Main(string[] args) { IExpression exp1 = new Add(new Value(1), new Value(2)); IExpression exp2 = new Mul(new Add(new Value(1), new Value(2)), new Value(2)); IExpression exp3 = new Sub(new Mul(new Add(new Value(1), new Value(2)), new Value(2)), new Value(1)); Console.WriteLine(exp1.Evaluate()); Console.WriteLine(exp2.Evaluate()); Console.WriteLine(exp3.Evaluate()); }