#include<iostream>
#include<string>
using namespace std;
int main(){
    string str;
    int i;
    cin>>str;
    i=a.length();
    if(str<0)
    {
        cout<<"Invalid input";
    }
    else if(str[i]=str[n-i-i])
    {
        cout<<"YES";
    }
    else (str[i]!=str[n-i-i]){
        cout<<"NO";
        
    }
    return 0;
    
}