Optional.java

import java.util.*;
import java.util.stream.LongStream;

class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        String name = scanner.nextLine();
        Optional<String> optAddress = AddressBook.getAddressByName(name);

        optAddress.ifPresentOrElse(address -> System.out.printf("%s lives at %s", name, address),
                () -> System.out.println("Unknown"));
    }
}

/* Please, do not modify the code below */
class AddressBook {
    private static Map<String, String> namesToAddresses = new HashMap<>();

    static {
        namesToAddresses.put("Pansy Barrows", "63 Shub Farm Drive, Cumberland, RI 02864");
        namesToAddresses.put("Kevin Bolyard", "9526 Front Court, Hartsville, SC 29550");
        namesToAddresses.put("Earl Riley", "9197 Helen Street, West Bloomfield, MI 48322");
        namesToAddresses.put("Christina Doss", "7 Lincoln St., Matawan, NJ 07747");
    }

    static Optional<String> getAddressByName(String name) {
        return Optional.ofNullable(namesToAddresses.get(name));
    }
}