using System;

using System.Linq;  

​

public class Program

{

    public static bool Check(string s)

        {

            if ( s == null ) return false;

            if ( s.Length != 8 ) return false;

            if ( !s.ToCharArray().Any(ch => char.IsDigit(ch))) return false;

            if ( s.Count(ch => char.IsUpper(ch)) != 1) return false;

​

            return true;

     }

    public static void Main()

    {

        Console.WriteLine(Check("Hello World"));

        Console.WriteLine(Check("Hel1owor"));

​

        Console.WriteLine(Check("azertyuy"));

​

        Console.WriteLine(Check("12345678"));

​

    }

}