#include<iostream>
#include<string>
#include<algirithm>
#include<cctype>
using namespace std;

bool isPalindrome(string s){
    string original = s;
    reverse(s.begin(),s.end());
    return original == s;
}

int main(){
    string input;
    getline(cin,input);
    
    if(input.length()>100){
        cout<<"INVALID INPUT";
        return 0;
    }
    
    if(input[0] == '-' || input.find('-')!=atring::npos){
        cout<<"INVALID INPUT";
        return 0;
    }
    
    string cleaned ="";
    for(char ch : input){
        if(isalnum(ch)){
            cleaned += tolower(ch);
        }
    }
    
    if(isPalindrome(cleaned)){
        cout<<"YES";
        
    }
    else{
        cout<<"NO";
        
    }
    return 0;
}