#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
using namespace std;

bool isPalindromes(string str) {
    string temp = "";
    
    for (char ch : str) {
        if (isalnum(ch)) {
            temp += tolower(ch);
        }
    }
    
    string rev = temp;
    reverse(rev.begin(), rev.end()); {
        
        if (str[0] == '-')
        return 0;
        
        if (str.find('-') != string::npos)
        return false;
        
        for (char ch : str) {
            if (!isalnum(ch) && !isspace(ch) && ch != ',')
            return false;
            
        }
        return true;
         
    }
    int main() {
        string input;
        getline(cin, input);
        
        if (input.length() > 100 || !isValidInput(input)) {
            cout << "Invalid Input";
            
        return 0;
        }
        if (isPalindromes(input))
        cout <<"YES";
        else
        cout << "NO";
    
    }
    return 0;
}