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

  _____     _____    _    _     ______    _  __  
 /  ___||  |  ___|| | |  | ||  /_   _//  | |/ // 
| // __    | ||__   | |/\| ||   -| ||-   | ' //  
| \\_\ ||  | ||__   |  /\  ||   _| ||_   | . \\  
 \____//   |_____|| |_// \_||  /_____//  |_|\_\\ 
  `---`    `-----`  `-`   `-`  `-----`   `-` --`