Java

import java.util.*;

public class CompanyUsers {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String command = sc.nextLine();

        LinkedHashMap<String, ArrayList<String>> hashMap = new LinkedHashMap<>();

        while (!command.equalsIgnoreCase("End")) {
            String[] input = command.split(" -> ");
            String name = input[0];
            String id = input[1];

            hashMap.putIfAbsent(name, new ArrayList<>());
                if(!hashMap.get(name).contains(id)){
                    hashMap.get(name).add(id);
                }


            command = sc.nextLine();
        }
        hashMap.entrySet()
                .stream()
                .sorted((e1, e2) -> e1.getKey().compareTo(e2.getKey()))
                .forEach(e -> {
                    System.out.printf("%s%n", e.getKey());
                    for (int i = 0; i < e.getValue().size(); i++) {
                        System.out.printf("-- %s%n", e.getValue().get(i));
                    }
                });
    }
}