how to auto increment jpg

Question

Hi all,

 

  Following code is storing one image after program run that image is base one Username_and current date , now what i want whenever same user put his detail at same day at that time his existing image of name and date should be increment like 1st time name should be john_1-10-2016, same user put his detail again then image should be john_1-10-2016(1),john_1-10-2016(2) and so on 

 

Bitmap bitmap = new Bitmap(Screen.PrimaryScreen.Bounds.Width,

Screen.PrimaryScreen.Bounds.Height);

Graphics graphics = Graphics.FromImage(bitmap as Image);

graphics.CopyFromScreen(0, 0, 0, 0, bitmap.Size);

var date = DateTime.Now.ToString("dd-MM-yyyy");

string format = txtname.Text += date;

bitmap.Save(@"E:\\Project backups\\Medical\\Sales_receipt\\" + format + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);