how to play

If you select the mark below and sandwich it like Othello（riversi)
The mark in between will also change to the mark that you put.
However, the marks between them must be the same.
If you put it in a different direction, the mark will change even if it is a different mark
It's clear if all the marks are the same!
It's a failure if you can't put the mark on the top right!
Let's play!