#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";
    return 0;
}
/**************************************************************
	Problem: 1647
	User: panjinyan
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/