Wei Wenzhong's little calculation

Dingbei!
"Great victory! Great victory in Shuofang!"
The messenger with three red flags on his back rushed into the west gate of Dingbei at a rapid speed.
Hearing what the messenger shouted, the soldiers guarding the city immediately started talking again.
"Another great victory in Shuofang?"
"No way?"
"Maybe it's a repeat of the great victory we had earlier?"
"How is that possible? It's been more than ten days since that great victory! It's impossible for the news to...