Simple Expression

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

class UserLogs
{
    static void Main()
    {
        string input = Console.ReadLine();
        List<string> nums = input.Split(new string[] { " ", "-", "+", "*", "/" }, StringSplitOptions.RemoveEmptyEntries).Where(s => !string.IsNullOrWhiteSpace(s)).ToList();
        input = Regex.Replace(input, " ", "");

        string pattern = @"[0-9.]+";
        string[] math = Regex.Split(input, pattern);

        decimal count = decimal.Parse(nums[0]);

        for (int i = 0; i < math.Length; i++)
        {
            if (math[i] == "+")
            {
                count += decimal.Parse(nums[i]);
            }
            else if (math[i] == "-")
            {
                count -= decimal.Parse(nums[i]);
            }
            else if (math[i] == "*")
            {
                count *= decimal.Parse(nums[i]);
            }
            else if (math[i] == "/")
            {
                count /= decimal.Parse(nums[i]);
            }
        }
        Console.WriteLine("{0:F9}", count);
    }
}