How to Find Max/Min value in a ListBox

Question

Hi Guys,
I am new at c sharp and I would like to know how I can find a min and max value in a listBox.
lets say I have a listbox which gets the elements from a text box and by a btn click events like this:

int intItems = (int)Convert.ToInt32(txtInput.Text);
listBox1.Items.Add(intItems);

I know how to get count and sum and average of these elements

could you please let me know how I can find these values(Max, Min)?
Regards