cache

diff --git a/src/main/java/br/ufrgs/inf/prosoft/cache/tools/Reducer.java b/src/main/java/br/ufrgs/inf/prosoft/cache/tools/Reducer.java
index c9deb3d..2e06138 100644
--- a/src/main/java/br/ufrgs/inf/prosoft/cache/tools/Reducer.java
+++ b/src/main/java/br/ufrgs/inf/prosoft/cache/tools/Reducer.java
@@ -90,6 +90,9 @@ public class Reducer {
                 while (iterator.hasNext()) {
                     Map.Entry<Long, Integer> entry = iterator.next();
                     accumulated += entry.getValue();
+                    if (accumulated < 0) {
+                        accumulated = 0;
+                    }
                     entry.setValue(accumulated);
                 }
             });