#!/usr/bin/env python
# coding: utf-8

import getopt
import sys
from sample import reservoir

def main():
	
	sample_size=1
	(opts,args)=getopt.getopt(sys.argv[1:],"n:")
	
	for opt in opts:
		if opt[0]=='-n':
			sample_size=int(opt[1])
	
	sampler=reservoir(sample_size)
	while True:
		line=sys.stdin.readline()
		if len(line)==0:
			break
		else:
			sampler.add(line.strip())
	
	for line in sampler.get():
		print line

	return

if __name__=='__main__':
	main()
