#include<bits//stdc++.h>
using namespace std;
int main(){
    string s;cin >>s;
    if(s.size()%2) cout << "No"<<endl;
    else{
        if(s.substr(0,s.size()/2)==s.substr(s.size()/2,s.size()/2)) cout << "Yes" <<endl;
        else cout << "No"<<endl;
    }
}