Streamer.bot Temp Conversion

using System;

public class CPHInline
{
    public bool Execute()
    {
        // your main code goes here
        CPH.TryGetArg("input0", out string numberString);
        CPH.TryGetArg("input1", out string fromUnit);
        CPH.TryGetArg("input3", out string toUnit);
        CPH.TryGetArg("msgId", out string replyId);


        if ((numberString == "") || (fromUnit == null) || (toUnit == null))
        {
            CPH.TwitchReplyToMessage("Please provide a whole number and two units. I know Celsius (C), Fahrenheit (F), and Kelvin (K). Example usage: !temp 100 F to C", replyId);
            return false;
        }

        int convertedNumber;

        if (int.TryParse(numberString, out convertedNumber))
        {}
        else
        {
            CPH.TwitchReplyToMessage("Please use a whole number. Negative numbers are also accepted. Here's a correct usage example: !temp 100 F to C", replyId);
            return false;
        }


        string fromUnitLower = fromUnit.ToLower();
        string toUnitLower = toUnit.ToLower();

        switch ((fromUnitLower, toUnitLower))
        {
            case ("c", "f"):
                CPH.TwitchReplyToMessage($"{numberString}°C is about {Convert.ToInt32((convertedNumber * 1.8) + 32)}°F", replyId);
                break;
            case ("c", "k"):
                CPH.TwitchReplyToMessage($"{numberString}°C is about {Convert.ToInt32(convertedNumber + 273.15)}°K", replyId);
                break;
            case ("f", "c"):
                CPH.TwitchReplyToMessage($"{numberString}°F is about {Convert.ToInt32((convertedNumber - 32) / 1.8)}°C", replyId);
                break;
            case ("f", "k"):
                CPH.TwitchReplyToMessage($"{numberString}°F is about {Convert.ToInt32(((convertedNumber - 32) / 1.8) + 273.15)}°K", replyId);
                break;
            case ("k", "c"):
                CPH.TwitchReplyToMessage($"{numberString}°K is about {Convert.ToInt32(convertedNumber - 273.15)}°C", replyId);
                break;
            case ("k", "f"):
                CPH.TwitchReplyToMessage($"{numberString}°K is about {Convert.ToInt32(((convertedNumber - 273.15) * 1.8) + 32)}°F", replyId);
                break;
            case ("c", "c"):
            case ("f", "f"):
            case ("k", "k"):
                CPH.TwitchReplyToMessage("I'm sure you can figure this one out yourself", replyId);
                break;
            default:
                CPH.TwitchReplyToMessage("I only know Celsius (C), Fahrenheit (F), and Kelvin (K). Here's a correct usage example: !temp 100 F to C", replyId);
                break;
        }
        return true;
    }
}