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

int main(){
    string s; getline(cin,s);
    if(s.empty() || s.find(',') != string::npos ||
    (s[0]=='-' && s.size()>1 && all_of(s.begin()=1,s.end(),:: isdigit)) ||
    !all_of(s.begin(), s.end(), ::isalnum))
    cout << "INVALID INPUT";
else {
    string r=s; reverse(r.begin(), r.end());
    cout << (s==r ? "YES" : "NO");
    }
    return 0;
}