#!/usr/bin/env python
#Copyright Brian Brazil <bbrazil@netsoc.tcd.ie> 2006

import sys
import random

firsts = {}
links = {}
lasts = {}


def processLines():
	line = sys.stdin.readline()
	while '' != line:
		if line[-1] == '\n':
			line = line[:-1]
		words = [ x.lower() for x in line.split()]
		if 0 == len(words):
			line = sys.stdin.readline()
			continue
		
		addFirst(words[0])
		for i in range(len(words) -1):
			addLink(words[i], words[i+1])
		addLast(words[-1])

		line = sys.stdin.readline()

def addFirst(word):
	global firsts
	if firsts.has_key(word):
		firsts[word] += 1
	else:
		firsts[word] = 1

def addLink(first,second):
	global firsts
	if links.has_key(first):
		links[first].append(second)
	else:
		links[first] = [second]

def addLast(word):
	global Lasts
	if lasts.has_key(word):
		lasts[word] += 1
	else:
		lasts[word] = 1

def makeString():
	string = []
	if 0 == len(firsts): return ''
	current = random.sample(firsts.keys(),1)[0]
	while True:
		string.append(current)
		if lasts.has_key(current):
			if not links.has_key(current):
				return ' '.join(string)
			if 0 < random.randint(-lasts[current],len(links[current])):
				return ' '.join(string)
		current = random.sample(links[current],1)[0]
	

if '__main__' == __name__:
	processLines()
	for i in range(1000):
		print makeString()