#include <iostream>
#include <algorithm>
#include <string>
using namespace std;

int main()
{
    string str1;
    getline(cin, str1);
    string str2 = str1;
    reverse(str2.begin(),str2.end());
    if(str1.size() == 0) cout << "YES";
    else if(str1.size() % 2 == 0)
    {
        if(str1 == str2) cout << "YES";
        else cout << "NO";
    }
    else cout << "NO";
    return 0;
}