package test; import java.util.Scanner; public class test { public static void main(String[] args) { Scanner s = new Scanner(System.in); String string = s.nextLine(); char c[] = string.toCharArray(); if (c.length % 2 == 0) { for (int i = 0; i < c.length / 2; i++) { if (c[i] != c[i + c.length / 2]) { System.out.println("NO"); break; } else if (i <= c.length / 2) { System.out.println("YES"); } } } else { System.out.println("NO"); } // System.out.println(); s.close(); } }