program main
  implicit none
  integer::N,i,j,total=0
  integer::W(100)=0
  integer::is_possible(0:10000)=0
  read *, N, W(1:N)
  is_possible(0)=1
  do i=1,N
     do j=total, 0 , -1
        is_possible(j+W(i)) = is_possible(j)+is_possible(j+W(i))
     end do
     total = total + W(i)
  end do

  if((MOD(total,2).eq.1) .or. (is_possible(total/2).eq.0)) then
     print '(a)','impossible'
  else
     print '(a)','possible'
  endif
end program main