// editor2
#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
using namespace std;
bool ispalindrome(string s){
    string cleaned ="";
    for(char c:s){
        if(isalnum(c)){
            
        }
    }
    string reversed=cleaned;
    reverse (reversed.begin(),reversed.end());
    return cleaned ==reversed;
    
}
bool isvalidInput(string s){
    if(s.length()>100||s.empty())
    return false;
    
    if(s[0]=='-')
    return false;
    for(char c:s){
        if(!(isalnum(c)||isspace(c)||c==',')){
            
        }
        if(c=='.')
        return false;
    }
    return true;
    }
    int main(){
        string input;
        getline(cin,input);
        if(!isvalidInput(input)){
            cout<<"Invalid input";
            else{
                if(!ispalindrome(input))
                cout<<"YES";
                else
                cout<<"NO";
                
            }
    }return 0;
}