---

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

namespace Systems
{
    class Program
    {
        static char ToChar(int input)
        {
            switch (input % 16)
            {
                case 10:
                    return 'A';
                case 11:
                    return 'B';
                case 12:
                    return 'C';
                case 13:
                    return 'D';
                case 14:
                    return 'E';
                case 15:
                    return 'F';
            }
            return 'Z';
        }
        static string Reverse(string input)
        {
            string output = "";
            for (int i = input.Length - 1; i >= 0; i--)
            {
                output += input[i];
            }
            return output;
        }
        static string ToVosm(int input)
        {
            string output = "";
            while (input > 7)
            {
                output += input % 8;
                input /= 8;
            }
            output += input;
            return Reverse(output);
        }
        static string ToShest(int input)
        {
            string output = "";
            while (input > 15)
            {
                if ( input % 16 > 9)
                {
                    output += ToChar(input % 16);
                }
                else
                {
                    output += input % 16;
                }
                input /= 16;
            }
            if (input > 9)
            {
                output += ToChar(input);
            }
            else
            {
                output += input;
            }
            return Reverse(output);
        }
        
        static string SumVosm(string input1, string input2)
        {
            int buf = 0;
            string output = "";
            string temp = input1;
            int[,] tabl = new int[8, 8] { { 0, 1, 2, 3, 4, 5, 6, 7 },
                                          { 1, 2, 3, 4, 5, 6, 7, 10 },
                                          { 2, 3, 4, 5, 6, 7, 10, 11 },
                                          { 3, 4, 5, 6, 7, 10, 11, 12 },
                                          { 4, 5, 6, 7, 10, 11, 12, 13 },
                                          { 5, 6, 7, 10, 11, 12, 13, 14 },
                                          { 6, 7, 10, 11, 12, 13, 14, 15 },
                                          { 7, 10, 11, 12, 13, 14, 15, 16 }, };
            for (int i = 0; i < Math.Min(input1.Length, input2.Length); i++)
            {
                output += tabl[input1[i], input2[i]] % 10;
            }
            return output;
        }
        static void Main(string[] args)
        {
            Console.Write("Введите число: ");
            int input = int.Parse(Console.ReadLine());
            string vosm = Convert.ToString(input, 8);
            string shest = Convert.ToString(input, 16);
            Console.WriteLine($"Восьмеричная система: {vosm}; Шестнадцатеричная система: {shest}");
            string vosm_ = ToVosm(input);
            string shest_ = ToShest(input);
            Console.WriteLine($"Восьмеричная система: {vosm_}; Шестнадцатеричная система: {shest_}");
            Console.WriteLine($"Сложение восьмеричных чисел: {SumVosm(vosm,vosm_)}");
        }
    }
}