diff --git a/src/calc.rs b/src/calc.rs
index d2735bc..c8bea0c 100644
--- a/src/calc.rs
+++ b/src/calc.rs
@@ -1,31 +1,58 @@
-struct calcNode {
+use std::io::Error;
+
+#[derive(Clone)]
+struct CalcNode {
     item: Item,
-    left: Option<Box<calcNode>>,
-    right: Option<Box<calcNode>>,
+    left: Option<Box<CalcNode>>,
+    right: Option<Box<CalcNode>>,
 }
 
-impl calcNode {
-    pub fn new(item: Item, left: Option<Box<calcNode>>, right: Option<Box<calcNode>>) -> Self {
+impl CalcNode {
+    pub fn new(item: Item, left: Option<Box<CalcNode>>, right: Option<Box<CalcNode>>) -> Self {
         Self { item, left, right }
     }
 }
+#[derive(Clone)]
 pub enum Item {
     Num(i32),
     Oper(Operation),
 }
+#[derive(Clone)]
 pub enum Operation {
     Add,
     Sub,
     Div,
     Mult,
 }
-pub struct calcTree {
-    root: calcNode,
+pub struct CalcTree {
+    root: CalcNode,
 }
 
-impl calcTree {
+impl CalcTree {
     pub fn new(item: Item) -> Self {
-        let root = calcNode::new(item, None, None);
+        let root = CalcNode::new(item, None, None);
         Self { root }
     }
+    pub fn insert(&mut self, item: Item) {
+        use Item::*;
+        if let Oper(_) = item {
+            match &self.root.item {
+                Num(_) => self.root = CalcNode::new(item, Some(Box::new(self.root.clone())), None),
+                Oper(_) => panic!("fuck off"),
+            }
+        } else {
+            match &self.root.item {
+                Num(_) => panic!("fuck off"),
+                Oper(_) => {
+                    if let None = self.root.right {
+                        self.root.right = Some(Box::new(CalcNode::new(item, None, None)));
+                    } else if let None = self.root.left {
+                        self.root.left = Some(Box::new(CalcNode::new(item, None, None)));
+                    } else {
+                        self.insert(item)
+                    }
+                }
+            }
+        }
+    }
 }