--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/day1/exercise/missing_num.py	Thu Oct 08 18:59:47 2009 +0530
@@ -0,0 +1,16 @@
+str_range = '4-7, 9, 12, 15'
+
+ranges = str_range.split(',')
+
+lst = []
+for r in ranges:
+    vals = r.split('-')
+    if len(vals) == 2:
+       lst.extend(range(int(vals[0]), int(vals[1]) + 1))
+    else:
+       lst.append(int(vals[0]))
+
+set_range = set(lst)
+all_elems = set(range(min(lst), max(lst)))
+
+print all_elems - set_range