diff --git a/120 prog.py b/120 prog.py
new file mode 100644
index 0000000..3040633
--- /dev/null
+++ b/120 prog.py	
@@ -0,0 +1,13 @@
+print("natural numbers")
+n=1
+def exception1(n1):
+  try:
+    while True:
+      print(n1)
+      n1=n1+1
+      if(n1>20):
+        raise StopIteration
+  except StopIteration:
+    print("number exceeds limit")
+
+exception1(n)