Once upon a time, there was a girl who was sad every day. Her name was Sangsang.
In fact, Sangsang's daily sadness does not happen every day, but she will allocate it reasonably. For example, if there are two sad things on Saturday, then she will be sad on Saturday. If there is no sad thing on the weekend, Sangsang will take out one sad thing from Saturday and feel it again. So she is sad every day.
Intention: Sang Sang will always have her happy day