#include<bits/stdc++.h>
using namespace std;
int main() {
    string s, t="";
    getline(cin,s);
    
    if (s[0]=='-' || s.find('-')!=string::npos) {
        cout <<"INVALID INPUT";
        return 0;
}
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;
}