using System;

using System.Globalization;

​

​

public class Program

{

    public static void Main()

    {       

        Console.WriteLine(GetContrastingColor("fbe164"));  // Output: EDCBA9        

    }

​

​

    public static string GetContrastingColor(string hexColor)

    {

        // Ensure hex color is 6 digits long

        if (hexColor.Length != 6)

            throw new ArgumentException("Input hex color should be 6 digits long");

​

​

        // Split the hex color into red, green, and blue components

        var r = int.Parse(hexColor.Substring(0, 2), NumberStyles.HexNumber);

        var g = int.Parse(hexColor.Substring(2, 2), NumberStyles.HexNumber);

        var b = int.Parse(hexColor.Substring(4, 2), NumberStyles.HexNumber);

​

​

        // Calculate the contrasting colors

        r = 255 - r;

        g = 255 - g;

        b = 255 - b;

​

        return r.ToString("X2")+g.ToString("X2")+b.ToString("X2");

        // Combine the colors back into a single string and return

        //return $"{r:X2}{g:X2}{b:X2}";

    }

}