On Validate allow either the Added_User or an adminuser to edit

On Validate allow either the Added_User or an adminuser to edit

on validate - I want to allow either the Added_User or an adminuser to edit a record. Other users should not be able to edit the record. I've tried a few different statements at "on validate" but cannot get them to work. I am an admin and I attempt to edit another users record as the test. So far, test failed. Any help is welcome. Two examples are below of statements I've tried to use. 

>> I've tried this

if (input.Added_User  !=  zoho.loginuser)||(zoho.loginuser !=  zoho.adminuser)
{
    alert "You can only modify your own record";
    cancel submit;
}

>> also tried this

if (input.Added_User  !=  zoho.loginuser)
{
    alert "You can only modify your own record";
    cancel submit;
}
else if (zoho.loginuser  !=  zoho.adminuser)
{
    alert "Sorry";
    cancel submit;
}