how to enforce user to fill in either one of the text fields before submit

i have 2 text fields and input as numbers.

If the user fills in text field 1, then cannot fill in text field 2

if the user fills in text field 2, then cannot fill in text field 1

User is required to enter number in either of the text fields, but not both

user cannot submit the document until either of the text fields are filled in.

How to set this up?

I try conditional field, but errors out saying cannot loop