connecting multiple values by draing lines

[waterfall]

Hi,
Im developing a C# web application in VS2005.
Ive 2 textboxes for user input and a button. First textbox gets string as input(e.g, ItemA, ItemB etc.) Second textbox get int as input(1,2,3,4 etc).Button is meant to generate a diagram using GDI.
Here is a look at my form.
Item1 ----------- Preceding Item 1 -----------
Item 2 ------------ Preceding Item2 ----------
Item3 ----------- Preceding Item 3 ------------
Item4 ----------- Preceding Item4 ---------




What im trying to do is to draw a diagram using values from preceding item textbox. for example if user enters 2 in preceding item 2 texbox, itemB will be connecting to itemA .
Until now ive successfully achieved a diagram with single value input.
But what if user enters 2,3 or 1,2,3? I don’t know to handle multiple values.

Plz plz help me.