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

class Memento {
private:
 friend class Originator;

 Memento(const string& st) {
 _st = st;
 }

 void SetState(const string& st) {
 _st = st;
 }

 string GetState() {
 return _st;
 }

private:
 string _st;
};

class Originator {
public:
 Originator() {
 _mt = nullptr;
 }

 Originator(const string &st) {
 _st = st;
 _mt = nullptr;
 }

 Memento* CreateMemento() {
 return new Memento(_st);
 }

 void SetMemento(Memento* mt) {
 _mt = mt;
 }

 void RestoreToMemento(Memento* mt) {
 _st = mt->GetState();
 }

 string GetState() {
 return _st;
 }

 void SetState(const string& st) {
 _st = st;
 }

 void PrintState() {
 cout << _st << "..." << endl;
 }

private:
 string _st;
 Memento *_mt;
};

int main() {
 Originator *o = new Originator();
 o->SetState("old");
 o->PrintState();
 Memento *m = o->CreateMemento();
 o->SetState("new");
 o->PrintState();
 o->RestoreToMemento(m);
 o->PrintState();

 delete o;
 delete m;

 return 0;
}