Практикум 2, Задание 2, номер 11

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace mainSolution
{
    public class MyException : Exception
    {
        public MyException(string messege) : base(message: messege + "\n\n\n Exception founded by Decibit\n\n\n") { }
        public MyException() : base()
        {

        }
        public void Messsage()
        {
            Console.WriteLine("\n\n\n\n\n\n Invalid number, please enter a number from 1 to 10 \n\n\n\n\n\n");
        }


    }
    class Input
    {
        private static IEnumerator<string> getin()
        {
            while (true)
                foreach (string s in Console.ReadLine().Split().Where(x => x.Length > 0))
                    yield return s;
        }

        private IEnumerator<string> inp = getin();

        public string GetString() { inp.MoveNext(); return inp.Current; }
        public int GetInt() { return int.Parse(GetString()); }
        public long GetLong() { return long.Parse(GetString()); }
        public double GetDouble() { return double.Parse(GetString()); }
    }

    static class Program
    {

        static bool solve(string number)
        {
            int[] digits = new int[10];
            if (string.Compare(number, "9876543210") == 1)
                return false;
            for (int i = 0; i < number.Length; i++)
            {
                int cur = number[i] - '0';
                if (digits[cur] > 0)
                    return false;
                else
                    digits[cur]++;
            }
            return true;
        }
        static void Main(string[] args)
        {

            Input cin = new Input();
            string number = cin.GetString();
            Console.WriteLine(solve(number)? "YES" : "NO");
        }
    }

}