#include <iostream>
#include <algorithm>
#include <cctype>
#include <string>

using namespace std;

int main() {
    string s, t="";
    if (!getline(cin, s))
    return 0;
    
    if(s.length() > 100 || s.find("..") != string::npos || (!s.empty() && s[0]=='.')) {
        cout<<"Invalid input";
        return 0;
    }
    
    for(char c : s)
         if(isalnum(c)){
             t+=(char)tolower(c);
         }
    }     
    
    string r = t;
    reverse(r.begin(), r.end());
    if (t.empty()){
        cout << "Invalid input";
    }
    else{
        cout << (t == r ? "Yes" : "No");
    }
    
    return 0;
    
}