#include<stdio.h>#include<math.h>#include<string.h>char c1[100];boolnode(char s[]){char s1[100];int top =-1;int mid =strlen(s)/2-1;for(int i =0; i <= mid; i++){
top++;
s1[i]= s[i];}int next;if(strlen(s)%2==0)
next = mid +1;else
next = mid +2;for(int i = next; i <strlen(s); i++){if(s[i]!= s1[top--])break;}if(top ==-1)returntrue;elsereturnfalse;}intmain(){int ans =0;char s2[100];scanf("%s",s2);if(node(s2))printf("yes\n");elseprintf("no\n");return0;}