判断输入是否是一个回文串（即向前和向后读都是一样的字符序列）。

每个输入仅为一个字符串序列【即ID】，可以把ID看成任何以一个字母或下划线开头、由字母或者数字组成的字符串，字符串长度不超过50。每个测试数据为一行，要求程序能够一次处理多行测试数据。-Determine whether the input string is a palindrome (ie, read the same forward and backward sequence of characters). Each input that is just a sequence of strings [ID], can be any ID as a letter or underscore, letters or numbers from the string, the string length does not exceed 50. Test data for each line requires a program to handle multi-line test data.