convert jsp code to c#

Question

hi i want to convert this jsp code to c#...
JSP CODE---------------

ResultSet resultset4;
try {

Statement statement1 = connection.createStatement();
String strSQL = ("SELECT * FROM IllnessMaster");
resultset4 = statement1.executeQuery(strSQL);
while(resultset4.next())
{
str2 = resultset4.getString("IllnessId");//Here getting illness ID
dd = str2.length();//taking IllnessID length
str5 = str2.substring(1,dd);//here making IllnessId into two parts. because of it contain a charactor followed by number
int f = Integer.parseInt(str5);
if (n1<f) //the variable "n1" assign higest number
n1=f;
}
--------------------------------------------------------------
I HAD TRIED BUT IT'S GIVING ERROR------
String strSQL = ("SELECT * FROM IllnessMaster");
SqlCommand cmdSql = new SqlCommand(strSQL, conn);
conn.Open();

SqlDataReader r = cmdSql.ExecuteReader();

String str2 = "";
int dd = 0;
String str5 = "";
int n1 = 0;
String str3 = "";
int flag = 0;


while (r.Read())
{
str2 = r["IllnessId"].ToString();//Here getting illness ID
MessageBox.Show("str2=",str2.ToString());
dd = str2.Length;//taking IllnessID length
MessageBox.Show("dd=", dd.ToString());
/*LINE-1*/ str5 = str2.Substring(1+dd); //here making IllnessId into two parts. because of it contain a character followed by number
MessageBox.Show("str5=", str5.ToString());
int f = Convert.ToInt32(str5);

if (n1 < f) //the variable "n1" assign higest number
n1 = f;
}
----------ERROR IN LINE-1---------------------------------------------
Exception Details: System.ArgumentOutOfRangeException: startIndex cannot be larger than length of string.
Parameter name: startIndex