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