發送短信 : Interior fixed points of unit-sphere-preserving Euclidean maps

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