Exam 4. Orders

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;

public class _4_Orders {

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

        Map<String, TreeMap<String, Integer>> orders = new LinkedHashMap<>();
        for (int i = 0; i < count; i++) {
            String[] inputs = scan.nextLine().split("[^A-Za-z0-9]+");
            String product = inputs[2];
            String customer = inputs[0];
            Integer amount = Integer.parseInt(inputs[1]);
            if (!orders.containsKey(product)) {
                orders.put(product, new TreeMap<String, Integer>());
            }

            TreeMap<String, Integer> amounts = orders.get(product);
            int previousAmount = 0;
            if (amounts.containsKey(customer)) {
                previousAmount = amounts.get(customer);
            }

            amounts.put(customer, previousAmount + amount);
        }

        for (String product : orders.keySet()) {
            System.out.print(product + ": ");
            TreeMap<String, Integer> amounts = orders.get(product);
            boolean first = true;
            for (Map.Entry<String, Integer> pair : amounts.entrySet()) {
                if (!first) {
                    System.out.print(", ");
                }
                first = false;
                String customer = pair.getKey();
                int amount = pair.getValue();
                System.out.print(customer + " " + amount);
            }

            System.out.println();
        }
    }

}