diff --git a/mapper.py b/mapper.py
index 9fa3def..aee2933 100644
--- a/mapper.py
+++ b/mapper.py
@@ -1,14 +1,28 @@
 #!/usr/bin/env python
 import sys
+import string
 
 # get all lines from stdin
 for line in sys.stdin:
     # remove leading and trailing whitespace
     line = line.strip()
 
+    # make lowercase
+    line = line.lower()
+
+    # https://stackoverflow.com/questions/34860982/replace-the-punctuation-with-whitespace
+    # remove punctuation
+    punctuations = list(string.punctuation) 
+    for p in punctuations:
+        if p in line:
+            line = line.replace(p, '')
+
     # split the line into words; splits on any whitespace
     words = line.split()
 
     # output tuples (word, 1) in tab-delimited format
+    stopwords = set(['the', 'and', 'is', 'a', 'this', 'that', 'it', 'to', 'in', 'an', 'as'])
+
     for word in words:
-        print '%s\t%s' % (word, "1")
+        if word not in stopwords:
+            print '%s\t%s' % (word, "1")