import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Main {
    public static void main(String[] args) {
        Map<Integer, List<String>> multimap = new HashMap<>();

        // Adding values to the multimap
        multimap.put(1, new ArrayList<>());
        multimap.get(1).add("Alice");
        multimap.get(1).add("Amanda");

        multimap.put(2, new ArrayList<>());
        multimap.get(2).add("Bob");

        // Iterating over the multimap
        for (Map.Entry<Integer, List<String>> entry : multimap.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }

        // Adding another value to an existing key
        multimap.get(1).add("Arnold");
        System.out.println("Updated values for key 1: " + multimap.get(1));

        // Checking if a specific key exists
        if (multimap.containsKey(2)) {
            System.out.println("Found values for key 2: " + multimap.get(2));
        }

        // Using lambda to iterate
        multimap.forEach((key, value) -> System.out.println(key + ": " + value));
    }
}