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   _____    _____              _    _    __   __  
  / ___//  |  ___||     ___   | || | ||  \ \\/ // 
  \___ \\  | ||__      /   || | || | ||   \   //  
  /    //  | ||__     | [] || | \\_/ ||   / . \\  
 /____//   |_____||    \__ ||  \____//   /_//\_\\ 
`-----`    `-----`      -|_||   `---`    `-`  --` 
                         `-`

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發送短信 : Properties of attractive points in cat(0) spaces