using System;

using System.Collections.Generic;

using System.Globalization;

using System.Resources;

​

public class Program

{

    static void Main()

    {

        Console.Write("Input : ");

        string input = Console.ReadLine(); // 678+9

        List<string> pecah = input.Split('+', '-', '/', '*' ,'=').ToList();

       // Console.WriteLine(pecah[0]); untuk pengecekz

        //Console.WriteLine(pecah[1]);

        List<string> op = new List<string>();

        int checker = 0;// cek hasil kondisi

        int checker2 = 0;// cek symbol kondisi

        int c = 0;

        double res = 0;

        //Console.WriteLine(misal.Length);

        for (int i = 0; i < input.Length; i++) // apakah dia mengandung + - / *

        {

            if (input[i] == '+')

            {

                op.Add("+");

                checker2++;

            }

            else if (input[i] == '-')

            {

                op.Add("-");

                checker2++;

            }

            else if (input[i] == '*')

            {

                op.Add("*");

                checker2++;

            }

            else if (input[i] == '/')

            {

                op.Add("/");

                checker2++;

            }

        }

        res = Convert.ToInt32(pecah[c]);

        for (int i = 0; i < input.Length; i++)

        {//pecah = (1, 2, 3) a[0] = 1 a[1] = 2 a[2] = 3 pecah// [c] = 1 pecah[c + 1] = 2 ,,,,,, 1 + 2 + 3 = (3) + 3[0] + [0 + 1], c++, //[1] + [1 + 1]

            if (input[i] == '+')

            {// 1 2 // sergio[1]

                res = res + Convert.ToInt32(pecah[c + 1]);

                c++;

            }

            else if (input[i] == '-')

            {

                res = res - Convert.ToInt32(pecah[c + 1]);

                c++;

            }

            else if (input[i] == '*')

            {

                res = res * Convert.ToInt32(pecah[c + 1]);

                c++;

            }

            else if (input[i] == '/')

            {

                res = res / Convert.ToInt32(pecah[c + 1]);

                c++;

​

            }

            else if (input[i] == '=')

            {

                checker = c;

                break;

            }

            if (pecah[checker2] == "")//kalau number berikutnya kosong

            {

                checker = -2;

                break;

            }

            if (!input.Contains('='))//kalau tidak ada =

            {

                checker = -1;

                break;

            }

        }

        if (checker != -1 && checker == checker2&& checker != -2&& c != 0)//kondisi

        {

            Console.WriteLine("Output : " + res);

        }

        else

        {

            Console.WriteLine("invalid");

        }

    }

}