回文判断：对于一个从键盘输入的字符串，判断其是否为回文。回文即正反序相同。如“abba”是回文，而“abab”不是回文。-Palindrome judge: for a string from the keyboard input, determine whether the palindrome. Palindrome sequence that is the same as the pros and cons. Such as " abba"　is a palindrome, and the " abab"　is not a palindrome.