Rotation String, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

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

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //Your code goes here
            Console.WriteLine("Hello, world!");
            string[] words=new string[11]{"ptolemaic","retrograde", "supplant","undulate","xenoepist","asymptote","babka","banoffee","engender","karpatka","othellolagkage"};
            Console.WriteLine("rotation!"+ GetIndex(words).ToString());
            
        }
        
        public static int GetIndex(string[] str){
            
            int low=0;
            int high= str.Length-1;
            string first_word=str[0];
            int mid=0;
            
            while(low < high){
                 mid= ((high-low)/2+low);
                Console.WriteLine("Hello, world!" + low.ToString() );
                Console.WriteLine("Hello, world!" + high.ToString() );
                 Console.WriteLine("Hello, world!" + (str[mid] ));
                
                if(String.Compare(str[mid], first_word)>0){
                    low=mid;
                }else{
                    
                    high=mid;
                }
                if(low+1==high){
                    return mid;
                }
            }
            return 0;
                }
}
}

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