//回文数
#include
#include
int main(){
char a[101],s[101];
int i,len,mid,next,top;
gets(a);
len = strlen(a);
mid = len/2 - 1;
//这里的mid值是以å—符串的åºå·ä¸ºå‚考，包å«0ç‚¹ï¼Œä½†æ˜¯åœ¨æ ˆä¸ç¼ºå¤±ä»Ž1开始的
//printf("%d", mid);
top = 0;
for(i=0;i<=mid;i++)
s[++top] = a[i];
if(len%2 == 0)
next = mid+1;
else
next = mid+2;
for(i=next;i<=len-1;i++)
{
if(a[i] != s[top])
break;
top--;
}
if(top == 0)
printf("YES");
else
printf("NO");
getchar();getchar();
return 0;
}