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 JAVA (judge verdict: Accepted)

import java.util.*;
import java.io.*;

public class Main {

	static void solve (Scanner in, PrintWriter out, Methods ms) {
		
		TreeMap<String, ArrayList<Integer>> map = new TreeMap<>();
		
		while (in.hasNext() == true) {
		
			String key = in.next();
			int value = in.nextInt();
			
			if (map.containsKey(key) == false) {
				map.put(key, new ArrayList<>());
			}
			map.get(key).add(value);
		}
		
		for (Map.Entry<String, ArrayList<Integer>> e : map.entrySet()) {
			out.println(e.getKey());
			Collections.sort(e.getValue());
			for (int i = 0; i < e.getValue().size(); i++) {
				if (i != 0) out.print(" ");
				out.print(e.getValue().get(i));
			}
			out.println();
		}
		
	}



	public static void main (String[] args) {

		Scanner in = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		Methods ms = new Methods();
		solve(in, out, ms);
		in.close();
		out.close();
	}

	static class Methods {

		public void print (Object... ar) {System.out.println(Arrays.deepToString(ar));}

		public int max (int... ar) {Arrays.sort(ar); return ar[ar.length-1];}

		public int min (int... ar) {Arrays.sort(ar); return ar[0];}

		public long gcd (long a, long b) {return b > 0 ? gcd(b,a%b) : a;}

		public long lcm (long a, long b) {return a / gcd(a,b) * b;}

		public long factorial (int i) {
			if (i == 1) return 1;
			else return i * factorial(i-1);
		}

		public int manhat (int x1, int y1, int x2, int y2) {
			return Math.abs(x1 - x2) + Math.abs(y1 - y2);
		}

		public double euclid (double x1, double y1, double x2, double y2) {
			return Math.sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
		}

		public boolean isPrime (int n) {
			if (n == 2) return true;
			if (n < 2 || n % 2 == 0) return false;
			for (int i = 3; i <= Math.sqrt(n); i += 2) if(n % i == 0) return false;
			return true;
		}

	}

}