TreasureFinder* -howToLooping

using System;
using System.Text;
using System.Linq;

namespace TreasureFinder
{
    class MainClass
    {
        public static void Main(string[] args)
        {
            int[] numbers = Console.ReadLine().Split().Select(int.Parse).ToArray();
            string text = string.Empty;
            string type = string.Empty;
            string coordinates = string.Empty;
            while((text=Console.ReadLine())!="find")
            {
                int maxLength = Math.Max(numbers.Length, text.Length);// found maxLength
                StringBuilder sb = new StringBuilder(maxLength);
                for (int i = 0; i < maxLength; i++)
                {
                    sb.Append((char)(text[i] - numbers[i % numbers.Length]));// NB! how to looping
                }

                int startIndexType = sb.ToString().IndexOf('&') + 1;
                int endIndexType = sb.ToString().IndexOf('&', startIndexType + 1);
                int typeLength = endIndexType - startIndexType;
                type = sb.ToString().Substring(startIndexType, typeLength);

                int startIndexCoordinates = sb.ToString().IndexOf('<') + 1;
                int endIndexCoordinates = sb.ToString().IndexOf('>');
                int coordinatesLength = endIndexCoordinates - startIndexCoordinates;
                coordinates = sb.ToString().Substring(startIndexCoordinates, coordinatesLength);
                Console.WriteLine($"Found {type} at {coordinates}");
            }
        }
    }
}