import java.util.Optional;

public class Task011125 {
    public static void main(String[] args) {
        Optional<String> opt1 = Optional.ofNullable(null);
        Optional<String> opt2 = Optional.of("java");
        
        String result1 = opt1.or(()-> opt2).orElse("default");
        String result2 = opt2.filter(s -> s.length() > 10)
                           .or(()-> Optional.of("fallback"))
                           .get();
        
        System.out.println(result1);
        System.out.println(result2);
    }
}

import java.util.HashMap;
import java.util.Map;

public class Task041125 {
    public static void main(String[] args) {
        Map<String, Integer> map = new HashMap<>();
        
        String key = "key";
        System.out.print(map.put(key, 1) + " ");
        System.out.print(map.put(key, 2) + " ");
        System.out.print(map.putIfAbsent(key, 3) + " ");
        System.out.print(map.compute(key, (k, v) -> null) + " ");
        System.out.print(map.put(key, 4));
    }
}