Restricting admin from destroying own account using cancan

Question

Here is a snippet of my code from my ability class

if user.admin?
      can :manage, :all
      can :destroy, :all if != current_user

I am sure that you can figure out what I am trying to do here. I realize that destroy is included in manage and I am repeating myself there. Any suggestions?

EDIT Yjerem's answer was the correct one and I just changed it to fit my code. This is what it looks like.

 if user.admin?
      can :manage, :all
      cannot :destroy, User, :id => user.id

As Yjerem also said, in cancan, ability precedence states that the ability defined lower down trump the ones over them so an admin can manage all except what is defined under it using the code above.