https://knightzone.studio/2014/08/19/1867/uva%e4%b8%ad%e6%96%87%e7%bf%bb%e8%ad%af%ef%bc%9a10020%ef%bc%8dminimal-coverage%e6%9c%80%e5%b0%8f%e8%a6%86%e8%93%8b%e5%8d%80%e9%96%93/
#UVa中文翻譯:10020-Minimal coverage(最小覆蓋區間)