ReqEx for validating a value

[Jithesh]

In my workflow during a transition from Status A to Status B, the current assignee need to fill in a few details in a transition screen. one of the custom field is a dropdown value with following options:

1: Yes | No

2: Yes | Yes

3: No | No

4: No | Yes

I would like to allow transition only for last three option, kindly guide me with appropriate Regular Expression in the "Validator" to achieve this.