#include "bits/stdc++.h"

using namespace std;

using ll = long long;
using ld = long double;

const double PI = 3.1415926535897932384626433832795;

const int dx[] = { 0, 1, 0, -1 };
const int dy[] = { -1, 0, 1, 0 };

int gcd(int x, int y) { return y ? gcd(y, x % y) : x; }
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : x; }
int lcm(int x, int y) { return x / gcd(x, y) * y; }
ll lcm(ll x, ll y) { return x / gcd(x, y) * y; }

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	string s;
	cin >> s;

	int n = s.size();
	for (int i = 0; i < n; i++) {
		string a = s.substr(0, i);
		string b = s.substr(i, n);
		if (a == b) {
			cout << "YES" << endl;
			return 0;
		}
	}

	cout << "NO" << endl;
	return 0;
}