diff --git a/main/Face.pde b/main/Face.pde
index 63aefce..17708db 100644
--- a/main/Face.pde
+++ b/main/Face.pde
@@ -22,4 +22,4 @@ public class Face {
     System.out.println();
   }
   
-}
\ No newline at end of file
+}
diff --git a/main/HalfEdge.pde b/main/HalfEdge.pde
index 073cd34..113791a 100644
--- a/main/HalfEdge.pde
+++ b/main/HalfEdge.pde
@@ -234,7 +234,11 @@ public class HalfEdge {
     return result;
   }
   public HalfEdge getAnotherLeaving() {
-    return getprevious().gettwin(); 
+    if (this != getprevious().gettwin()) {
+      return getprevious().gettwin();
+    } else {
+      return null; 
+    }
   }
   
   public ArrayList<HalfEdge> getAllLeaving() {
diff --git a/main/main.pde b/main/main.pde
index 2b5670c..df6bff5 100644
--- a/main/main.pde
+++ b/main/main.pde
@@ -86,10 +86,10 @@ public void setup() {
   //h1.facePrint();
   //drawgraph.drawGraph(list.getPoints());
   //(new Face(h4, list)).printFace();
-  (new Face(h12, list)).printFace();
+  //(new Face(h12, list)).printFace();
 }
 void draw() {
-  background(255,255,255,0);
+  background(255);
   drawgraph.drawGraph(list.getPoints());
 }
 void keyPressed() {