using System;
using System.Text.RegularExpressions;
 
public class Test
{
public static void Main()
{
 
 
String input = @"Complaint listed in some portal is like below RequirementChanges caused disturbance of 200 hours of rework. Due to this there is a request reported in Excel.";
 
Regex rgx = new Regex(@"\S+(?=\s+caused disturbance)|\S+\s+\S+(?=\s+of rework)|(?<=\breported in\s+)\S+");
 
foreach (Match m in rgx.Matches(input))
Console.WriteLine(m.Groups[0].Value);
 
}
}

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