规则Rules：
四道标准数独。此外，每个灰色格两侧的两个数字一致。
Four Classic. Additionally, to each grey cells, the two numbers adjacent to it are same.
※本题将在一段时间后隐藏。This puzzle will be hidden after some hours.
※恭喜网站300题达成！Congratulations for the 300 puzzle of the website.
※此题曾在清华大学深圳国际研究生院线下活动时使用。This puzzle was used in Tsinghua SIGS offline activities.
