diff --git a/mapper.py b/mapper.py
index 9fa3def..0baf058 100644
--- a/mapper.py
+++ b/mapper.py
@@ -5,10 +5,13 @@
 for line in sys.stdin:
     # remove leading and trailing whitespace
     line = line.strip()
+    line = line.lower()
 
     # split the line into words; splits on any whitespace
     words = line.split()
+    stopwords = set(['the','and','a','I','.',',','!','or','for','not','in','on','to','an','be','but','of','is','it'])
 
     # output tuples (word, 1) in tab-delimited format
     for word in words:
+       if word not in stopwords:
         print '%s\t%s' % (word, "1")