#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

int main() {
    string input;
    getline(cin, input);
    
    // Convert to lowercase
    transform(input.begin(), input.end(), input.begin(), ::tolower);
    
    // Remove middle character if odd length
    if (input.length() % 2 != 0) {
        input.erase(input.length() / 2, 1);
    }
    
    // Split the string
    int halfLength = input.length() / 2;
    string firstHalf = input.substr(0, halfLength);
    string secondHalf = input.substr(halfLength);
    
    // Compare and output result
    if (firstHalf == secondHalf) {
        cout << "YES" << endl;
    } else {
        cout << "NO" << endl;
    }
    
    return 0;
}