#include <bits/stdc++.h> using namespace std; int a[1000]; int main(){ string s; getline(cin, s); int i=s.size()-1; int j=0; while((j<i)&&(s[j]==s[i])) { i--; j++; } if(j>=i) cout<<"yes"<<endl; else cout<<"no"<<endl; return 0; }