#!/usr/bin/python

import sys

c = 3

if len(sys.argv) < 3:
	print "Usage: peek <filename> <line number> [no. of context lines]"
	sys.exit(0)


l = -1

try:
	l = int(sys.argv[2])
except ValueError:
	print "Invalid number: " + sys.argv[2]
	print "Usage: peek <filename> <line number> [no. of context lines]"
	sys.exit(0)
			

if len(sys.argv) == 4:
	try:
		c = int(sys.argv[3])
	except ValueError:
		print "Invalid number: " + sys.argv[3]		
		print "Usage: peek <filename> <line number> [no. of context lines]"
		sys.exit(0)


f = open(sys.argv[1])
count = 0

try:
	line = f.readline()
	while line:
		count = count + 1

		if abs(l - count) <= c:
			print line,

		if count > l + c:
			break

		line = f.readline()

finally:
	f.close()