def prototype(name,bases,dict):
 	cls = type(name, bases,dict)
 	cls.prototype = cls
 	return cls
 
 __metaclass__ = prototype
 
 from copy import deepcopy
 
 class prototyped_object:
    def clone(self):
       c = self.prototype()
       c.__dict__ = deepcopy(self.__dict__)
       return c
 
 
 class Char:
   toplevels = set()
 
   def __init__(self, val):
     self.char = val
     self.successors = set()
     if self not in self.toplevels:
       self.toplevels.add(self)
     else:
       self.__dict__ = (set([self]) & self.toplevels).pop().__dict__
 
   def set_toplevel(self):
     item = (self.toplevels | set([self])).pop()
     item.merge(self)
  #   print item
     self.toplevels.add(item)
 
   def merge(this, other):
     for x,y in zip(this.successors, other.successors):
       x.merge(y)
       x.successors = x.successors | y.successors
 
   def clone(self, val):
       c = self.prototype(val)
       return c
   def __hash__(self):
     return hash(self.char)
   def __cmp__(self, other):
     try:
       return cmp(self.char, other.char)
     except AttributeError:
       return cmp(self.char, other)
   def process_word(self, word):
     if self.char == word[0]:
       try:
         new = self.clone(word[1])
         if word[1] in self.successors:
           new = (set([word[1]]) | this.successors).pop()
         new.process_word(word[1:])
         self.successors.add(new)
       except IndexError:
         pass
 
   def print_(self, depth=0):
     print '-'*depth+self.char
     for i in self.successors:
       i.print_(depth+1)
 
 
 
 def process_text(text):
   text = ( x.strip() for x in text.replace('\n', ' ').expandtabs().split(' ') if x.strip().isalpha() and len(x.strip()) > 1 )
   for i in text:
     x = Char(i[0])
     x.process_word(i)
 #    x.set_toplevel()
 
 import random
 def randword():
   string = []
   x = random.choice(tuple(Char.toplevels))
   string.append(x.char)
 
   while x.successors:
     x = random.choice(tuple(x.successors))
     string.append(x.char)
   return ''.join(string)
 
 import sys
 string = file(sys.argv[1]).read()
 
 process_text(string)
 #[ q.print_() for q in Char.toplevels ]
 
 #for x in range(10000):
 while raw_input() != 'q':
 	print randword()