列出文件中用户名部分相同的邮件地址和相同的次数，并写到文件result.txt中，用户名部分只出现一次的邮件地址不用输出和写到文件中。-document listed user name part of the same e-mail address and the same number, and wrote papers result.txt, user name appeared only once part of the e-mail addresses and do not have