diff --git a/README.md b/README.md
index 828cb57..a3990ae 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,7 @@
 - Circle: S = πR²
 - Rectangle: S = ab
 - Square: S = a²
+- Сylinder side surface:S = πRH 
 
 ## Perimeter
 - Circle: P = 2πR