diff --git a/CreatingReliableSoftwareCpp/Presentation/exercises/observer/src/Core/include/Core/Time.h b/CreatingReliableSoftwareCpp/Presentation/exercises/observer/src/Core/include/Core/Time.h
index 8a5e089..f35d3c0 100644
--- a/CreatingReliableSoftwareCpp/Presentation/exercises/observer/src/Core/include/Core/Time.h
+++ b/CreatingReliableSoftwareCpp/Presentation/exercises/observer/src/Core/include/Core/Time.h
@@ -6,6 +6,14 @@ class TimeObserver;
 #include <string>
 #include <set>
 #include <utility>
+#include <set>
 
 class Time {
+	size_t _day{0};
+	std::set<TimeObserver*> obs_list;
+	public:
+	void attach(TimeObserver *obs);
+	void detach(TimeObserver *obs);
+	Time& operator++();
+	size_t day();
 };
diff --git a/CreatingReliableSoftwareCpp/Presentation/exercises/observer/src/Core/include/Core/TimeObserver.h b/CreatingReliableSoftwareCpp/Presentation/exercises/observer/src/Core/include/Core/TimeObserver.h
index 106a258..fd5e84f 100644
--- a/CreatingReliableSoftwareCpp/Presentation/exercises/observer/src/Core/include/Core/TimeObserver.h
+++ b/CreatingReliableSoftwareCpp/Presentation/exercises/observer/src/Core/include/Core/TimeObserver.h
@@ -1,5 +1,6 @@
 #pragma once
 
 struct TimeObserver {
+	void next_day();
 
 };
diff --git a/CreatingReliableSoftwareCpp/Presentation/exercises/observer/src/Core/src/Time.cpp b/CreatingReliableSoftwareCpp/Presentation/exercises/observer/src/Core/src/Time.cpp
index 0ab265b..e7dba9b 100644
--- a/CreatingReliableSoftwareCpp/Presentation/exercises/observer/src/Core/src/Time.cpp
+++ b/CreatingReliableSoftwareCpp/Presentation/exercises/observer/src/Core/src/Time.cpp
@@ -4,3 +4,18 @@
 
 #include <algorithm>
 #include <functional>
+
+// size_t _day;
+// std::set<TimeObserver*> obs_set;
+void Time::attach(TimeObserver *obs){
+	obs_set.insert(obs);
+}
+void Time::detach(TimeObserver *obs){
+
+}
+Time& Time::operator++(){
+
+}
+size_t Time::day(){
+
+}