diff --git a/src/main/java/Algorithm/Graph.java b/src/main/java/Algorithm/Graph.java
index c12e21d8900de25f2a6a326b13ccf165ba576d6e..d539471711f8d68605ae00ee5673b87e2f998983 100644
--- a/src/main/java/Algorithm/Graph.java
+++ b/src/main/java/Algorithm/Graph.java
@@ -386,6 +386,7 @@ public class Graph {
 			int id = (int)(fst % shift) ;
 			for (int neighbor : this.AdjList.get(id)) {
 				if (degen [neighbor] > degen [id]) {
+					set.remove(degen [neighbor] * shift + neighbor);
 					degen [neighbor] -- ;
 					set.add(degen [neighbor] * shift + neighbor) ;
 				}