  o    X  o    X  o    X  o</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 6   o    X  o    X  o    X  o</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 7   o    X  o    X  o    X  o</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 8   o    X  o    X  o    X  o</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 9   o    X  o    X  o    X  o</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 10  o    X  o    X  o    X  o</span>
<span class="r-in