1 package firs;
2
3 import java.util.Scanner;
4
5 public class Digui {
6 private static int a;
7 private static int b=0;
8 public static void ok(String str,int i)
9 {
10 if(i==a/2||i==a/2+1)
11 {
12 System.out.println("yes");
13 }
14 else
15 {
16 if(str.charAt(i-1)==str.charAt(b))
17 {
18 i--;
19 b++;
20 ok(str,i);
21 }
22 else
23 {
24 System.out.println("no");
25 }
26 }
27 }
28 public static void main(String[] args) {
29 Scanner input=new Scanner(System.in);
30 String str;
31 str=input.next();
32 a=str.length();
33 ok(str,a);
34 }
35 }