编写程序，验证一个字符串是否为回文串：是否从前读它和从后读它都是一样的。例如，mom，dad是回文串。该程序接收用户输入的字符串，判断是否为回文串，然后将判断的结果输出。在验证回文串时，忽略大小写、空格和标点。示例输出如图所示。(Write a program to verify whether a string is a palindrome string: whether it was read before and after reading it is the same. For example, mom, Dad are palindrome strings. The program receives the string inputted by the user, judges whether it is palindrome string, and outputs the result of judgment. Ignore the size, space and punctuation when verifying the palindrome string. The example output is shown in figure.)