What does the following Java code output?

import java.util.HashMap;
import java.util.Map;
public class Main {
    public static void main(String[] args) {
        Map<Integer, String> users = new HashMap<>();
        users.put(1, "Alice");
        users.put(2, "Bob");
        users.put(1, "Charlie");
        System.out.println(users.get(1));
    }
}