#include <iostream>

#include <string> 

using namespace std;

int main(){

string a,b;

bool c=true;

cin>>a;

if (a.length()%2==1) c=false;

for (int i=0;i<a.length()/2;i++) b+= a[i];

for (int i=0;i<a.length()/2;i++) if (a[i]!=a[a.length()-1-i]) c=false;

if (c) cout<<"YES"<<"\n"<<b;

else cout<<"NO";

return 0;

}