#include<iostream>
using namespace std;

int main()
{
    string s, t ="";
    getline(cin, s);
    
    if(s.length() > 100)
    {
        cout<<"INVALID INPUT";
        return 0;
    }
    
    for(char c: s)
    {
        if(c =='-' || c=='.')
        {
            cout<<"INVALID INPUT";
            return 0;
        }
    }
    if(isalnum(c))
        t+=tolower(c);
    if(t=="")
    {
        cout<<"INVALID INPUT";
        return 0;
    }
    string r =t;
    reverse(r.begin(),r.end());
    
    if(t==r)
    {
        cout<<"YES";
    }
    else
    {
        cout<<"NO";
    }
    return 0;
}