Creating a condition for a form's item

Creating a condition for a form's item

Hi guys,

I created a simple form that contains three items:

1. Gender (Male, Female) = radio button
2. List of 50 Males names = multi select item
3. List of 50 Females names = multi select item

I just need any user who selects 'male' from the gender's item would only SEE the list of 'male names' and who selects 'female' from the gender's item would only SEE the list of 'female names'.

The other condition is that each user must not select more than FOUR names from his/her list. How could I enforce this in my form???

My knowledge of creating scripts in form is nothing. So Please HELP!

Thank you in advance