diff --git a/Data-Structures/Trees/09-pre-order-iterative.md b/Data-Structures/Trees/09-pre-order-iterative.md
index 5af7112..d4d2b17 100644
--- a/Data-Structures/Trees/09-pre-order-iterative.md
+++ b/Data-Structures/Trees/09-pre-order-iterative.md
@@ -46,7 +46,7 @@ public:
             if (root->left != NULL) {
                 st.push(root->left);
             }
-            
+
         }
         return ans;
     }
diff --git a/Data-Structures/Trees/10-post-order-twoStack.md b/Data-Structures/Trees/10-post-order-twoStack.md
index 6418bd2..e7cf321 100644
--- a/Data-Structures/Trees/10-post-order-twoStack.md
+++ b/Data-Structures/Trees/10-post-order-twoStack.md
@@ -51,7 +51,7 @@ public:
                 st1.push(root->right);
             }
         }
-        
+
         while(!st2.empty()){
             ans.push_back(st2.top()->val);
             st2.pop();