public class StringNode {
    private char ch;
    private StringNode next;
    
    public StringNode(char c, StringNode n) {
        ch = c;
        next = n;
    }
        
    public static StringNode copy(StringNode str) {
        if (str == null) {
            return null;
        }

        StringNode copyRest = copy(str.next);
        return new StringNode(str.ch, copyRest);    
    }
    
    public static void main(String[] args)  {
        StringNode s1 = new StringNode('t', null);
        s1 = new StringNode('a', s1);
        s1 = new StringNode('c', s1);

        StringNode copied = StringNode.copy(first);
    }
}