Add getVocabSize

Change-Id: I642b39b1186752387da2b555b6e6cb20a0952be5
diff --git a/lib/IDS/DeReKoVecs/derekovecs-server.c b/lib/IDS/DeReKoVecs/derekovecs-server.c
index b2cdb20..2234c66 100644
--- a/lib/IDS/DeReKoVecs/derekovecs-server.c
+++ b/lib/IDS/DeReKoVecs/derekovecs-server.c
@@ -1185,3 +1185,7 @@
   fclose(f);
   return (0);
 }
+
+unsigned long getVocabSize() {
+  return (unsigned long) words;
+}