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