program main
  implicit none
  integer::N,total,i,j, total_weight
  integer::W(100)
  integer::dp_memo(0:5000,1:100)
  data dp_memo/500100*0/
  read *, N, W(1:N)
  total = SUM(W(1:N))
  if(MOD(total,2).eq.1) then
     print '(a)','impossible'
     return
  end if
  do i=N,1,-1
     do j=0,total/2
        if(j.lt.W(i)) then
           dp_memo(j,i) = dp_memo(j, i+1)
        else
           dp_memo(j,i) = MAX(dp_memo(j,i+1),dp_memo(j-W(i), i+1)+W(i))
        endif
     end do
  end do
  if(dp_memo(total/2, 1).eq.total/2) then
     print '(a)','possible'
  else
     print '(a)','impossible'
  end if
end program main