import java.util.*;

public class Task171025 {
    public static void main(String[] args) {
        Queue<Integer> queue = new LinkedList<>();
        queue.offer(1);
        queue.offer(2);
        queue.offer(3);
        
        System.out.print(queue.peek() + " ");
        System.out.print(queue.poll() + " ");
        queue.offer(4);
        System.out.print(queue.remove() + " ");
        System.out.print(queue.element() + " ");
    }
}

import java.util.Optional;

public class Task201025 {
    public static void main(String[] args) {
        Optional<String> optional = Optional.of("hello");
        Optional<String> filtered = optional.filter(s -> s.length() > 10);
        Optional<String> mapped = optional.map(s -> null);
        
        System.out.println(filtered.isPresent());
        System.out.println(mapped.isPresent());
        System.out.println(optional.orElse("world"));
        System.out.println(filtered.orElse("java"));
    }
}

import java.util.PriorityQueue;

public class Task211025 {
    public static void main(String[] args) {
        PriorityQueue<Integer> pq = new PriorityQueue<>();
        pq.offer(5);
        pq.offer(2);
        pq.offer(8);
        pq.offer(1);
        
        System.out.print(pq.poll() + " ");
        System.out.print(pq.poll() + " ");
        
        pq.offer(0);
        pq.offer(3);
        
        System.out.print(pq.poll() + " ");
        System.out.print(pq.poll() + " ");
        System.out.print(pq.poll());
    }
}

import java.util.LinkedList;

public class Task221025 {
    public static void main(String[] args) {
        LinkedList<Integer> list = new LinkedList<>();
        list.add(1);
        list.add(2);
        list.add(3);
        
        list.remove(1);
        list.remove(new Integer(2));
        
        System.out.println(list.size());
        System.out.println(list.get(0));
    }
}

import java.util.ArrayDeque;
import java.util.Deque;

public class Task231025 {
    public static void main(String[] args) {
        Deque<Integer> deque = new ArrayDeque<>();
        deque.offer(1);
        deque.push(2);
        deque.offer(3);
        deque.push(4);
        
        System.out.print(deque.poll() + " ");
        System.out.print(deque.pop() + " ");
        System.out.print(deque.remove() + " ");
        System.out.print(deque.element());
    }
}

import java.util.concurrent.*;

public class Task241025 {
    public static void main(String[] args) throws InterruptedException {
        BlockingQueue<Integer> queue = new ArrayBlockingQueue<>(2);
        
        System.out.print(queue.offer(1) + " ");
        System.out.print(queue.offer(2) + " ");
        System.out.print(queue.offer(3, 100, TimeUnit.MILLISECONDS) + " ");
        
        System.out.print(queue.poll() + " ");
        System.out.print(queue.offer(3) + " ");
        System.out.print(queue.poll() + " ");
        System.out.print(queue.poll() + " ");
    }
}

import java.util.TreeSet;

public class Task271025 {
    public static void main(String[] args) {
        TreeSet<Integer> set = new TreeSet<>();
        set.add(5);
        set.add(3);
        set.add(8);
        set.add(1);
        
        System.out.print(set.lower(4) + " ");
        System.out.print(set.higher(4) + " ");
        System.out.print(set.floor(3) + " ");
        System.out.print(set.ceiling(6));
    }
}

import java.util.HashSet;

public class Task281025 {
    public static void main(String[] args) {
        HashSet<String> set1 = new HashSet<>();
        set1.add("hello");
        set1.add("world");
        
        HashSet<String> set2 = new HashSet<>();
        set2.add("world");
        set2.add("hello");
        
        System.out.println(set1.equals(set2));
        System.out.println(set1 == set2);
        
        HashSet<String> set3 = set1;
        set3.add("java");
        
        System.out.println(set1.contains("java"));
        System.out.println(set2.contains("java"));
    }
}

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

public class Task291025 {
    public static void main(String[] args) {
        Map<String, Integer> map = new HashMap<>();
        map.put("a", 1);
        map.put("b", 2);
        map.put("a", 3);
        map.putIfAbsent("b", 4);
        map.putIfAbsent("c", 5);
        
        System.out.println(map.get("a"));
        System.out.println(map.get("b"));
        System.out.println(map.get("c"));
        System.out.println(map.getOrDefault("d", 6));
    }
}

import java.util.HashMap;

public class Task301025 {
    public static void main(String[] args) {
        HashMap<Key, String> map = new HashMap<>();
        
        Key k1 = new Key(1);
        Key k2 = new Key(1);
        Key k3 = new Key(2);
        
        map.put(k1, "first");
        map.put(k2, "second");
        map.put(k3, "third");
        
        k1.value = 2;
        
        System.out.println(map.get(k1));
        System.out.println(map.get(k2));
        System.out.println(map.get(k3));
        System.out.println(map.size());
    }
    
    static class Key {
        int value;
        Key(int value) { this.value = value; }
        
        public boolean equals(Object o) {
            return o instanceof Key && ((Key) o).value == this.value;
        }
        
        public int hashCode() {
            return value;
        }
    }
}