發送短信 : Number of 4-kings in bipartite tournaments with no 3-kings

           __   __             __   __    ______  
    ___    \ \\/ //     ___    \ \\/ //  /_   _// 
   /   ||   \ ` //     /   ||   \ ` //   `-| |,-  
  | [] ||    | ||     | [] ||    | ||      | ||   
   \__ ||    |_||      \__ ||    |_||      |_||   
    -|_||    `-`'       -|_||    `-`'      `-`'   
     `-`                 `-`