diff --git a/src/include/parser.h b/src/include/parser.h
index c4d54d9..f14c6db 100644
--- a/src/include/parser.h
+++ b/src/include/parser.h
@@ -1,6 +1,7 @@
 #ifndef DEF_PARSER_H
 #define DEF_PARSER_H
 
+#include <vector>
 #include "tokenize.h"
 using namespace std;
 
@@ -17,8 +18,8 @@ ExprStatement ->
 
 Expr ->
     | T
-    | T + S
-    | T - S
+    | T + Expr
+    | T - Expr
 
 T ->
     | F
@@ -26,12 +27,12 @@ T ->
     | F / T
     | F % T
 
-F ->
-    | U
-    | - F
-    | + F
-
 U ->
+    | F
+    | - U
+    | + U
+
+F ->
     | (Expr)
     | Identifier
     | Number
@@ -42,30 +43,28 @@ enum class NodeType {
     Prog, //                  -> Instruction; Prog
     AssignedDeclaration, //   -> Type Identifier = Expr
     Declaration, //           -> Type Identifier
-    Plus, //                  -> T + S
-    Minus, //                 -> T - S
+    Plus, //                  -> T + Expr
+    Minus, //                 -> T - Expr
     Mult, //                  -> F * T
     Div, //                   -> F / T
     Mod, //                   -> F % T
     UnaryMinus, //            -> -F
     UnaryPlus, //             -> +F
     Parenthesis, //           -> (Expr)
-    Assignment, //            -> Identifier = Expr
-    Leaf
+    Assignment //             -> Identifier = Expr
 };
 
-struct Node {
+struct InnerNode {
     NodeType type;
-    Node* children;
+    vector<Node> children;
 };
 
 
 // A Leaf is always corresponding to a Token
-enum class TreeType { Leaf, Node };
-struct SyntaxTree {
-    TreeType type;
+struct Node {
+    bool is_leaf;
     union {
-        Node node;
+        InnerNode node;
         Token leaf;
     };
 };