diff --git a/utils.h b/utils.h
index 2aa8d1b..976f555 100644
--- a/utils.h
+++ b/utils.h
@@ -16,7 +16,7 @@ namespace utils{
             end = std::chrono::high_resolution_clock::now();
         }
         double cost(){
-            return std::chrono::duration_cast<std::chrono::nanoseconds>(end-start).count();
+            return double( std::chrono::duration_cast<std::chrono::nanoseconds>(end-start).count())/1000000000.0;
         }
     private: