diff --git a/examples/happy birthday.py b/examples/happy birthday.py
new file mode 100644
index 0000000..2455584
--- /dev/null
+++ b/examples/happy birthday.py	
@@ -0,0 +1,22 @@
+class Affine(object):
+   DIE = 128
+   KEY = (7, 3, 55)
+   def __init__(self):
+      pass
+   def encryptChar(self, char):
+      K1, K2, kI = self.KEY
+      return chr((K1 * ord(char) + K2) % self.DIE)
+		
+   def encrypt(self, string):
+      return "".join(map(self.encryptChar, string))
+   
+   def decryptChar(self, char):
+      K1, K2, KI = self.KEY
+      return chr(KI * (ord(char) - K2) % self.DIE)
+   
+   def decrypt(self, string):
+      return "".join(map(self.decryptChar, string))
+
+affine = Affine()
+wish = affine.decrypt('{*RcQb!/[?*R')
+print (wish)