4th corner for 3/4 or 4/4 shift
<a href="//commons.wikimedia.org/wiki/User:YLSS" title="User:YLSS">YLSS</a> and <a href="//commons.wikimedia.org/wiki/User:Pi.1415926535" title="User:Pi.1415926535">Pi.1415926535</a>
2020-08-22
<span class="int-own-work" lang="en">Own work</span>