diff --git a/src/Tree.java b/src/Tree.java
index a712e81..d1c6644 100644
--- a/src/Tree.java
+++ b/src/Tree.java
@@ -72,15 +72,14 @@ public class Tree {
         Node rightChild = father.getRigthChild();
         switch (father.getNode()) {
             case '!' :
-                Node child = leftChild.getLeftChild();
                 switch (leftChild.getNode()){
                     case '!':
-
+                        Node child = leftChild.getLeftChild();
                         appliedGreatFather(father, child);
                         break;
                     case '|' :
-                        Node lc = child.getLeftChild();
-                        Node rc = child.getRigthChild();
+                        Node lc = leftChild.getLeftChild();
+                        Node rc = leftChild.getRigthChild();
 
                         Node notlc = new Node(null,lc,null,'!', lc.getLvl() +1);
                         Node notrc = new Node(null,rc,null,'!', rc.getLvl() +1);
@@ -93,8 +92,8 @@ public class Tree {
                         appliedGreatFather(father, greatfather);
                         break;
                     case '&' :
-                        Node lc_2 = child.getLeftChild();
-                        Node rc_2 = child.getRigthChild();
+                        Node lc_2 = leftChild.getLeftChild();
+                        Node rc_2 = leftChild.getRigthChild();
 
                         Node notlc_2 = new Node(null,lc_2,null,'!', lc_2.getLvl() +1);
                         Node notrc_2 = new Node(null,rc_2,null,'!', rc_2.getLvl() +1);
@@ -107,8 +106,8 @@ public class Tree {
                         appliedGreatFather(father, greatfather_2);
                         break;
                     case '>' :
-                        Node lc_3 = child.getLeftChild();
-                        Node rc_3 = child.getRigthChild();
+                        Node lc_3 = leftChild.getLeftChild();
+                        Node rc_3 = leftChild.getRigthChild();
 
                         Node notrc_3 = new Node(null,rc_3,null,'!', rc_3.getLvl() +1);
                         rc_3.setFather(notrc_3);
@@ -145,7 +144,9 @@ public class Tree {
         } else if (father.getPos() == 2) {
             father.getFather().setRigthChild(greatFather);
             greatFather.setFather(father);
-        } else
+        } else {
             root = greatFather;
+            greatFather.setFather(null);
+        }
     }
 }
\ No newline at end of file