四个数字有多少种组合不重复公式

简介：Since the second year of Chongzhen, every time the Jianlu invaders entered the fortress, they caused huge losses to the Ming Dynasty. There was panic inside and outside. There were countless people who were kidnapped and cities that were breached and burned. The financial losses were even greater. It is incalculable. Everyone in the court, from the emperor to the petty officials, felt sad every time they mentioned Jianlu entering the fortress.