/**
 * "On the fly"-code of the first exercise on
 * 30/04/2009 (augmented with some comments).
 *
 * Compile with:
 *   javac Homework.java
 * Run with:
 *   java Homework <file>
 */

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.util.Map;
import java.util.StringTokenizer;
import java.util.TreeMap;

public class Homework {
	// delimiter of our comma separated file
	public static String delim = ",";
	
	
	public static void main(String args[]) {
		/* we don't care about errors and wrap
		 * the whole code into a try-catch block
		 */
		try {
			/* Create a bufferedReader and initialized it with
			 * the first argument given on the commandline
			 * as filename. The bufferedReader allows linewise
			 * reading of the file.
			 */
			FileReader fi = new FileReader(new File(args[0]));
			BufferedReader br = new BufferedReader(fi);
			
			/* variable to hold the current line, while we read the
			 * file linewise.
			 */
			String line = null;
			
			// Tokenizer to get the values separated by the delimiter.
			StringTokenizer strToken = null;
			
			/* StudentName (first column) and
			 * Points (second column)
			 */
			String studentName = null;
			int points = 0;
			/* variable to calculate intermediate values, while we 
			 * aggregate the point data.
			 */
			int interm = 0;
			
			/* Key-ordered Map datastructure, to hold the current data, we are
			 * calculating.
			 * A Map is a structure which maps key-values to data.
			 * For example:
			 * 	{studentName1 -> 1, studentName2 -> 5, ..., studentNameN -> 10}
			 * 
			 * Since the TreeMap is ordered after key values, we don't care about
			 * sorting in the end.
			 */
			Map<String, Integer> studentPoints = new TreeMap<String, Integer>();
			
			// read the file linewise
			while ((line = br.readLine()) != null) {
				strToken = new StringTokenizer(line, delim);
				
				// get the data of interest (first and last column)
				studentName = strToken.nextToken();
				strToken.nextElement();
				points = Integer.parseInt(strToken.nextToken());
				
				// calculation of the total sum
				if (studentPoints.containsKey(studentName)) {
					interm = studentPoints.get(studentName).intValue();
					studentPoints.put(studentName, new Integer(interm + points));
				} else {
					studentPoints.put(studentName, new Integer(points));
				}
			}
			
			/* print out the result */
			for (String student : studentPoints.keySet()) {
				System.out.println(student + " -> "  + studentPoints.get(student).toString());
			}
		} catch (Exception exc) {
			// exception handling
			exc.printStackTrace();
		}
	}
}