//迴文偵測
#include <iostream>
using namespace std;
string input;
int sizestr , n;
bool test;
int main() {
  cin >> input;
  sizestr = input.size();
  n = sizestr/2;//以前半的str跑迴圈
  for (int i = 0 ; i<= n-1 ; i++){
    if(input[i] == input[sizestr-i-1]){
      test = true;
    }else{
      test = false;
      break;
    }
  }
  if(sizestr == 1){
    //一個字也算迴文
    test = true;
  }  
  if(test == true){
    cout << "yes";
  }else{
    cout << "no";
  }
}