    &lt;NA&gt;</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 3                                                                                                             &lt;NA&gt;</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 4                                                                                                             &lt;NA&gt;</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 5                                                                 