规则Rules：
标准数独基础上，圆圈格子填奇数，方块格子填偶数。
Classic rules applied. Additionally, circle cells contain odd numbers, square cells contain even numbers.
◆例题 Example
◆在线涂鸦 Draw it Online
◆在线做 Do it by CTC
◆在线做 Do it by Penpa
