The Updrome problem

You all are heard about the "Palindromes" but there is one more term we introduced that is "UPdromes", The string $s$ is said to be a "UPdromes"....... Let's consider the reverse string of $s$ is $x$, such that $s[i]$!=$x[i]$ for all $i$..... You are given a string $s$, your task is to check whether the string $s$ is "UPdrome" or not. Print "YES"(without inverted comma's) , if the string $s$ is