#include <iostream>
#include <string>
using namespace std;

class Context { };

class Expression {
public:
 virtual ~Expression() { }
 virtual void Interpret(const Context& c) = 0;
};

class TerminalExpression :public Expression {
public:
 TerminalExpression(const string& statement) {
 _statement = statement;
 }

 void Interpret(const Context& c) {
 cout << this->_statement << " -- TerminalExpression" << endl;
 }

private:
 string _statement;
};

class NonterminalExpression :public Expression {
public:
 NonterminalExpression(Expression* expression, int times) {
 _expression = expression;
 _times = times;
 }

 void Interpret(const Context& c) {
 for (int i = 0; i < _times; i++) {
 _expression->Interpret(c);
 }
 }

private:
 Expression *_expression;
 int _times;
};

int main() {
 Context *c = new Context();
 Expression *tp = new TerminalExpression("echo");
 Expression *ntp = new NonterminalExpression(tp, 4);
 ntp->Interpret(*c);

 delete ntp;
 delete tp;
 delete c;

 return 0;
}