diff --git a/ex4.md b/ex4.md
index 5f07c75..f6c83a5 100644
--- a/ex4.md
+++ b/ex4.md
@@ -16,4 +16,7 @@
 
 	`https://gitea.com/emiliagnatiuk/programowanie-obiektowe.git`
 
-	`https://github.com/julpac5/julpac5`
\ No newline at end of file
+	`https://github.com/julpac5/julpac5`
+
+	Remark: It is possible that a friend is using the same name for a class (e.g. Sequence). In such a case
+	one has to ask the friend to add the code to some namespace (just like namespace std, but different). In this way there should be no more issues with conflicting names.
\ No newline at end of file