diff --git a/LeetCodeSharp.Tests/P589Tests.cs b/LeetCodeSharp.Tests/P589Tests.cs
index 1ba123e..50748c5 100644
--- a/LeetCodeSharp.Tests/P589Tests.cs
+++ b/LeetCodeSharp.Tests/P589Tests.cs
@@ -1,4 +1,4 @@
-using LeetCodeSharp.Problems;
+using LeetCodeSharp.Problems589;
 using LeetCodeSharp.Utils;
 
 namespace LeetCodeSharp.Tests;
diff --git a/LeetCodeSharp/LeetCodeSharp.csproj b/LeetCodeSharp/LeetCodeSharp.csproj
index e3bf522..b719c27 100644
--- a/LeetCodeSharp/LeetCodeSharp.csproj
+++ b/LeetCodeSharp/LeetCodeSharp.csproj
@@ -6,8 +6,4 @@
 		<Nullable>disable</Nullable>
 	</PropertyGroup>
 
-	<ItemGroup>
-	  <Folder Include="Problems\" />
-	</ItemGroup>
-
 </Project>
diff --git a/LeetCodeSharp/Problems/p589_n_ary_tree_preorder_traversal.cs b/LeetCodeSharp/Problems/Solution589.cs
similarity index 93%
rename from LeetCodeSharp/Problems/p589_n_ary_tree_preorder_traversal.cs
rename to LeetCodeSharp/Problems/Solution589.cs
index c1fe2f1..b4e066a 100644
--- a/LeetCodeSharp/Problems/p589_n_ary_tree_preorder_traversal.cs
+++ b/LeetCodeSharp/Problems/Solution589.cs
@@ -6,7 +6,7 @@
 using LeetCodeSharp.Utils;
 using System.Collections.Generic;
 
-namespace LeetCodeSharp.Problems
+namespace LeetCodeSharp.Problems589
 {
 
     // Submission codes start here
@@ -30,7 +30,7 @@ public class Node {
 }
 */
 
-    public partial class Solution
+    public class Solution
     {
         public IList<int> Preorder(Node root)
         {
diff --git a/LeetCodeSharp/Problems/Solution590.cs b/LeetCodeSharp/Problems/Solution590.cs
new file mode 100644
index 0000000..f33e21c
--- /dev/null
+++ b/LeetCodeSharp/Problems/Solution590.cs
@@ -0,0 +1,61 @@
+/**
+* [N-ary Tree Postorder Traversal] 590
+*/
+
+using System.Collections.Generic;
+using LeetCodeSharp.Utils;
+
+namespace LeetCodeSharp.Problems590
+{
+
+    // Submission codes start here
+
+    /*
+// Definition for a Node.
+public class Node {
+    public int val;
+    public IList<Node> children;
+
+    public Node() {}
+
+    public Node(int _val) {
+        val = _val;
+    }
+
+    public Node(int _val, IList<Node> _children) {
+        val = _val;
+        children = _children;
+    }
+}
+*/
+
+    public class Solution
+    {
+        public IList<int> Postorder(Node root)
+        {
+            var dfs = new Dfs();
+
+            dfs.Search(root);
+            return dfs.Result;
+        }
+
+        private class Dfs
+        {
+            public IList<int> Result { get; } = new List<int>();
+
+            public void Search(Node node)
+            {
+                if (node == null) return;
+
+                foreach (var child in node.children)
+                {
+                    Search(child);
+                }
+
+                Result.Add(node.val);
+            }
+        }
+    }
+
+    // Submission codes end here
+}
\ No newline at end of file