using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

​

namespace baitap

{

    class Program

    {

        public static void inputSTT(int stt, char c)

        {

            int n;

            while(true){

                Console.WriteLine("nhap n:");

                n = Convert.ToInt32(Console.ReadLine());

                if(n>0 && n< 90+stt){

                    break;

                } else {

                    Console.WriteLine("nhap lai n");

                }

            }

            for(int i = 1; i<=n;i++){

                Console.Write(i+c);

            }

        }

        static void Main(string[] args)

        {

            int n;

            Console.Write("nhap vao stt:");

            n = Convert.ToInt32(Console.ReadLine());

            inputSTT(n,'#');

        }

    }

}

​