#include<bits/stdc++.h>

using namespace std;

bool check(string s, int l, int r){
    if(l >= r) return true;
    if(s[l] != s[r]) return false;
    return check(s, l+1, r-1);
}

int main(){
    string s;
    cin >> s;
    int n = s.size();
    if(check(s, 0, n-1)){
        cout << "YES";
    }
    else cout << "NO";
}