#include<iostream>
#include<string>
using namespace std;
int main()
{
    string s;
    getline(cin,s);
    if(s[0]=='-')
    {
        cout<<"INVALID INPUT";
        return 0;
    }
    string t="";
    for (char c: s);
    char c;
    if(isalnum(c))t+=tolower(c);
    string r=t;
    reverse(r.begin(),r.end());
    cout<<(t==r ? "YES" : "NO");
    return 0;
}