Zadacha

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

namespace zadacha
{
    class Program
    {

        static void Main(string[] args)
        {
            read reass = new read();
            reass.chisk();
        }
    }
    class read
    {
        static string line;

        public void chisk()
        {
            System.IO.StreamReader file =
        new System.IO.StreamReader(@"c:\in.txt");
            line = file.ReadLine();
         int  [] cifrint = new int [line.Length];
         for (int i = 0; i < line.Length; i++)
         {
             cifrint.SetValue((int)Char.GetNumericValue(line[i]), i);
         }
         for (int i = 0; i < cifrint.Length; i++)
         {
             switch (i)
             {
                 case 0:
                     cifrint[i] = cifrint[i] * 2;
                     break;
                 case 1 :
                     cifrint[i] = cifrint[i] * 7;
                     break;
                 case 2:
                     cifrint[i] = cifrint[i] * 6;
                     break;
                 case 3:
                     cifrint[i] = cifrint[i] * 5;
                     break;
                 case 4:
                     cifrint[i] = cifrint[i] * 4;
                     break;
                 case 5:
                     cifrint[i] = cifrint[i] * 3;
                     break;
                 case 6:
                     cifrint[i] = cifrint[i] * 2;
                     break;
             }
         }
             int sum = 0;
             foreach (int value in cifrint)
             {
                 sum += value;
             }
             int ostatok = sum % 11;
             vivod(ostatok);
         }

             public void vivod (int ostatok)
             {
                 string bukva = "";
                 switch (ostatok)
                 {
                     case 0:
                         bukva = "J";
                         break;
                     case 1:
                         bukva = "A";break;
                     case 2:
                         bukva = "B";break;
                     case 3:
                         bukva = "C";break;
                     case 4:
                         bukva = "D";break;
                     case 5:
                         bukva = "E";break;
                     case 6:
                         bukva = "F";break;
                     case 7:
                         bukva = "G";break;
                     case 8:
                         bukva = "H";break;
                     case 9:
                         bukva = "I";break;
                     case 10:
                         bukva = "Z";break;
                 }
                 System.IO.File.WriteAllText(@"C:\out.txt", bukva);
             }
         }

        }