#!/bin/env python2.6
"""
Read lines in BED format (tab-delimited) from STDIN and print out only gene
names (4th column).

DO NOT pipe any BED header lines to this program!

Usage:
    grep -v ^track sample_data.bed | ./BME_205_Python_lecture_firstProg
"""

import sys

for line in sys.stdin:
    line   = line.rstrip ('\n\r')  # not needed here, but generally a good idea
    fields = line.split ('\t')     # split line on tab character
    if len (fields) < 4:
        print >> sys.stderr, \
              "Bad BED line!  Not enough fields.  Here is the line:\n", \
              line
        sys.exit (1)
    else:
        print fields[3]