#include<iostream>
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<='9'&&a>='0')
    {
        cout<<"YES";
    }
    else
    {
        cout<<"NO";
    }
}