// editor2
#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
using namespace std;
int main(){
    string input;
    getline(cin,input);
    if(input.length()>100){
        cout<<"Invalid input";
        return 0;
        
    }
    if(input.find('-')!=string::npos||input.find('.')!=string::npos){
        cout<<"Invalid input";
        return 0;
        
    }
    string cleaned="";
    for(char ch:input){
        if(isalnum(ch)){
            cleaned+=tolower(ch);
            }
        }
        if(cleaned.empty()){
            cout<<"Invalid input";
            return 0;
        }
        string reversed =cleaned;
        reverse(reversed.begin(),reversed.end());
        if(cleaned==reversed){
            cout<<"YES"
        }else{
            cout<<"NO";
        
        }
    }
    return 0;
}