#include <bits/stdc++.h> 
using namespace std;
int main()
{
    char a;
    cin >> a;
    if (a>='a' && a<='z') cout << "YES";
    else if (a>='A' && a<='Z') cout << "YES";
    else if (a>='0' && a<='9') cout << "YES";
    else cout << "NO";
    return 0;
}