#include<bits/stdc++.h>
using namespace std;
int main(){
	int a,b,c,d,e;
	cin>>a;
	b=a/1000;
	c=a/100%10;
	d=a/10%10;
	e=a%10;
	if(b*10+c==e*10+d){
		cout<<"yes";
	}else cout<<"no";
}
/**************************************************************
	Problem: 1647
	User: panyuchen
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/