diff --git a/mathematics/mcmc_2.ipynb b/mathematics/mcmc_2.ipynb
index 50eb7ac..ad6f72e 100644
--- a/mathematics/mcmc_2.ipynb
+++ b/mathematics/mcmc_2.ipynb
@@ -745,3 +745,4 @@
  "nbformat": 4,
  "nbformat_minor": 1
 }
+cout<<"hello"