#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
using namespace std;
bool ispalindrome(string s){
    string cleaned ="";
    for(char c:s){
        if(isalnum(c)){
            cleaned +=tolower(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==',')){
            return false;
            
        }
        if(c=='-')
        return false;
    }
    return true;
    {
        int main(){
            string input;
            getline(cin,input);
            if(!svalidinput(input)){
                cout<<"INVALID INPUT";
            }
        }
        else{
            if(ispalindrom(input))
            cout<<"YES";
            else
            cout<<"NO";
        }
        return 0;
    }
}