Exam 4. Logs Aggregator

import java.util.HashMap;
import java.util.Map.Entry;
import java.util.Scanner;
import java.util.TreeMap;
import java.util.TreeSet;

public class _4_LogsAggregator {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner scan = new Scanner(System.in);
        int count = scan.nextInt();
        scan.nextLine();

        TreeMap<String, Integer> durations = new TreeMap<>();
        HashMap<String, TreeSet<String>> ipAddresses = new HashMap<>();

        for (int i = 0; i < count; i++) {
            String ipStr = scan.next();
            String userName = scan.next();
            String durStr = scan.next();
            int duration = Integer.parseInt(durStr);

            Integer previousDuration = durations.get(userName);
            if (previousDuration == null) {
                previousDuration = 0;
            }
            durations.put(userName, previousDuration + duration);

            TreeSet<String> ipSet = ipAddresses.get(userName);
            if (ipSet == null) {
                ipSet = new TreeSet<>();
            }
            ipSet.add(ipStr);
            ipAddresses.put(userName, ipSet);

            scan.nextLine();
        }

        for (Entry<String, Integer> userNameAndDuration : durations.entrySet()) {
            String userName = userNameAndDuration.getKey();
            int duration = userNameAndDuration.getValue();
            TreeSet<String> ipSet = ipAddresses.get(userName);
            System.out.println(userName + ": " + duration + " " + ipSet);
        }
    }

}