#include <iostream>
#include <cctype>
#include <string>
#include <algorithm>
using namespace std;
int main(){
    string s,t="";
    getline(cin,s);
    if(s.find('-')!=string::npos||s.find('-')!=string::npos){
        cout<<"Invalid input";
        return 0;
    }
    for(char c:s)
       if(isalnum(c))+tolower(c);
    if(t.empty()){
        cout<<"Invalid input";
        return 0;
    }
    string r=t;
    reverse(r.begin(),r.end());
    cout<<t==r?"YES":"NO");
}