using System;
using System.Text.RegularExpressions;

publicclass Example
{
   publicstaticvoid Main()
   {
      string pattern = @"\b[A-Z]+\b(?=\P{P})";
      string input = "If so,what comes next?";
      foreach (Match match in Regex.Matches(input,pattern,RegexOptions.IgnoreCase))
         Console.WriteLine(match.Value);
   }
}
// The example displays the following output:
//       If
//       what
//       comes