I have a picklist field 'address type' values are us ,canada and foreign.If I select US and Canada the billing state should show list of predefined values and for ,address type' is selected as foreign the billing state should be text field and should be able to enter any value.We are using visual force pages.Please help me on this

I have a picklist field 'address type' values are us ,canada and foreign.If I select US and Canada the billing state should show list of predefined values and for ,address type' is selected as foreign the billing state should be text field and should be able to enter any value.We are using visual force pages.Please help me on this

I have a picklist field 'address type' values are us ,canada and foreign.If I select US and Canada the billing state should show list of predefined values and for ,address type' is selected as foreign the billing state should be text field and should be able to enter any value.We are using visual force pages.Please help me on this