四个数字有多少种组合方式

简介：Emperor Chongzhen gritted his teeth and said nothing. Of course he knew that he should send troops, but a few days ago, during the Battle of the Canal, he was worried about the safety of the prince and had already sent Tang Tong out. However, Tang Tong never returned and was intercepted by the prince. If the canal defense line is broken, where can we send troops now? There are mostly infantry in the capital city now, and infantry cannot find the prince quickly.