public static void Main()
var piCode = "PI-1000001";
var CurrentProformaCode = "PI-1000001_R2";
if(CurrentProformaCode.Contains("_R"))
var currentId = Convert.ToInt32(CurrentProformaCode.Split('_')[1].ToString().Replace("R", ""));
var newID = currentId + 1;
var revicedCode = CurrentProformaCode.Substring(CurrentProformaCode.IndexOf('_'), 1).ToString() + "R" + newID;
Console.WriteLine(newID);
Console.WriteLine(CurrentProformaCode);
Console.WriteLine(revicedCode);
Console.WriteLine("Hello World");