#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";
}
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