diff --git a/cpp/2205/220521-CN.cpp b/cpp/2205/220521-CN.cpp
new file mode 100644
index 0000000..7fd685c
--- /dev/null
+++ b/cpp/2205/220521-CN.cpp
@@ -0,0 +1,24 @@
+#include <vector>
+#include <unordered_set>
+
+/**
+ * 961. N-Repeated Element in Size 2N Array
+ * You are given an integer array nums with the following properties:
+ * - nums.length == 2 * n.
+ * - nums contains n + 1 unique elements.
+ * - Exactly one element of nums is repeated n times.
+ * Return the element that is repeated n times.
+ */
+
+class Solution {
+public:
+    static int repeatedNTimes(const std::vector<int>& nums) {
+        std::unordered_set<int> s;
+        for (int i : nums) {
+            if (s.count(i))
+                return i;
+            s.insert(i);
+        }
+        return -1;
+    }
+};
diff --git a/cpp/2205/CMakeLists.txt b/cpp/2205/CMakeLists.txt
index 119a00a..15e1b64 100644
--- a/cpp/2205/CMakeLists.txt
+++ b/cpp/2205/CMakeLists.txt
@@ -3,4 +3,4 @@ PROJECT(2205)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2205 220521.cpp)
+ADD_EXECUTABLE(2205 220521-CN.cpp)