diff --git a/AcWing/84/84.cpp b/AcWing/84/84.cpp
new file mode 100644
index 00000000..5bdfa075
--- /dev/null
+++ b/AcWing/84/84.cpp
@@ -0,0 +1,8 @@
+class Solution {
+  public:
+    int getSum(int n) {
+        int r = n;
+        n && (r += getSum(n - 1));
+        return r;
+    }
+};