public class List<T>
{
    private Node<T> first;
    
    public List() {
        first = null;
    }
    
    public boolean isEmpty() {
        if (first == null) return true;
        return false;
    }
    
    public int size() {
        Node<T> current = first;
        int count = 0;
        
        while (current != null) {
            count++;
            current = current.next;
        }
        
        return count;
    }
    
    public T get(int n) {
        
     Node<T> current = first;
        
        for (int i = 0; i < n; i++) {
            if (current == null) return null;
            current = current.next;
        }
        
        if (current == null) return null;
        return current.wert;
    }
    
    public void add(T val) {
        Node<T> neu = new Node<T>();
        neu.wert = val;
        
        if (first == null) {
            first = neu;
        } else {
            Node<T> current = first;
            while (current.next != null) {
                current = current.next;
            }
            current.next = neu;
        }
    }
    
    public void add(int n, T val) {
        if (n >=size()) {
            add(val);
            return;
        }
        Node<T> neu = new Node<T>();

        neu.wert = val;
        
        if (n==0){
            neu.next = first;
            first = neu;
            return;
        }
        Node<T> current = first;
        for (int i = 0; i < n-1; i++){
            current = current.next;
        }
        neu.next = current.next;
        current.next = neu;
        
    }
    
    public boolean contains(T val) {
        Node<T> current = first;
        
        while (current != null) {
            if (current.wert.equals(val)) return true;
        }
        
        return false;
    }
    
    public T remove(int n) {
        if (n >= size()) return null;
        if (n == 0) {
            T tmp = first.wert;
            return tmp;
        }
        Node<T> current = first;
        
        for (int i = 0; i< n-1; i++)
        {
            current = current.next;
        }
        T tmp = current.next.wert;
        current.next = current.next.next;
        return tmp;
        
    }
    public String toString(){
        String result = "";
        Node<T> current = first;
        while (current != null) {
            result += current.wert + ", ";
            current = current.next;
        }
        return result;
    }
}