How to add a exact number of items to listbox from textbox.

Question

if (textBox1.Text != "" || textBox1.Text != "")

{

if (!listBox1.Items.Contains(textBox1.Text))

{

   listBox1.Items.Add(textBox1.Text);

   textBox1.Text = "";

}

 

I can add items to listbox by above code,

but i am not getting how to add exact number of items to listbox through textbox, For eg: i want to add only 7 items in listbox, if i try to add 8th item it should not take it. i know its normal question but i m new in C# could someone please help me.