http://acm.hdu.edu.cn/showproblem.php?pid=1686 Time Limit: 3000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 31930 Accepted Submission(s): 12181 Problem Description The French author Georges Perec (1936–1982) once wrote a book, La disparition, w...