PHP script

Hi!
I'm a newbie in php but by searching and reading in drupal.org I've managed to create my php snippet for login destination. It works fine.
Looks something like this:

global $user;
if (in_array('role1', $user->roles)) {
    return 'node1';
}  
if (in_array('role2', $user->roles)) {
    return 'node2'; 
}else {
    return '<front>';
}

Now, what i want to do is to redirect a user with more than one role. For example, I want that user with only role1 or only role2 assigned be redirected to the correspondent node, but I want that a user that has been assigned with role1 and role2 be redirected to another node, say node3.
I've tried to add to the code above:

if (in_array('role1', $user->roles)) && if (in_array('role2', $user->roles))  {
    return 'node3';
}  

and later

if (in_array('role1', $user->roles)) AND if (in_array('role2', $user->roles))  {
    return 'node3';
}  

but i'm having no success, it keeps redirecting user with two roles to frontpage.

Probably this is a super simple question, perhaps syntax related but i don't understand much of php...