Problem:
Book Index

Books are indexed. Write a program which reads a list of pairs of a word and a page number, and prints the word and a list of the corresponding page numbers.

You can assume that a word consists of at most 30 characters, and the page number is less than or equal to 1000. The number of pairs of a word and a page number is less than or equal to 100. A word never appear in a page more than once.

The words should be printed in alphabetical order and the page numbers should be printed in ascending order.

Input

word page_number
:
:

Output

word
a_list_of_the_page_number
word
a_list_of_the_Page_number
:
:

Sample Input

style 12
even 25
introduction 3
easy 9
style 7
document 13
style 21
even 18

Output for the Sample Input

document
13
easy
9
even
18 25
introduction
3
style
7 12 21

Solution in Ruby (judge verdict: Accepted)

index = Hash.new([])

$<.readlines.map do |l|
  a = l.chomp.split
  [a.first, a.last.to_i]
end.each {|word, page| index[word] += [page]}

index.keys.sort.each {|k| puts k, index[k].sort.join(" ")}