#include<bits/stdc++.h>
using namespace std;

int main() {
	char str[100], stack[100];
	int  i, len, mid, next, top;

	fgets(str, sizeof(str), stdin);
	len = strlen(str);
	mid = len / 2 - 1;//求字符串的中点

	top = 0;//初始化栈
	for (i = 0; i <= mid; i++) { //将mid前的字符依次压入堆栈
		stack[++top] = str[i];
	}

	//判断字符串长度是奇数还是偶数，以决定需要匹配的后半部分起始下标
	next = (len % 2) ? (mid+2) : (mid+1);

	//开始匹配
	for (i = next; i <= len - 1; i++) {
		if (str[i] != stack[top]) break;
		top--;
	}

	//验证结果
	if (top == 0)
		printf("YES\n");
	else
		printf("No\n");

	return 0;
}