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

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發送短信 : On r-cross intersecting families of sets