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

int main()
{

    string str;
    cin >> str;
    int n = str.size();
    if(n!=5){
        cout << "ERROR";
        return 0;
    }
    if(str[0]!= str[3]){
            if(str[1] - str[4] == 2 || str[1]- str[4] == - 2){
                    if(str[1] >='9' || str[4] >='9'){


                        if(str[0] && str[3] <= 'H'){
                            if(str[1] && str[4] <='8'){
                                cout << "YES";
                            }
                    }else{
                        cout << "ERROR";
                    }
                }else{
                    cout << "ERROR";
                }
            }else{
                cout << "NO";
            }
    }else{
        cout << "NO";
    }



}