! dynamic programing with memo
! recursive for remain_capacity
! dp_memo(cap, indx)
recursive function rc_dp(W, capacity, indx, N, dp_memo) result(total_weight)
  implicit none
  integer,intent(in) ::W(:)
  integer::total_weight,capacity,indx, N
  integer,allocatable::dp_memo(:,:)

  if(dp_memo(capacity, indx).ne.-1) then
     total_weight = dp_memo(capacity, indx)
  else if(capacity.lt.W(indx)) then
     total_weight = rc_dp(W, capacity, indx+1, N, dp_memo)
     dp_memo(capacity, indx) = total_weight
  else
     total_weight = MAX(rc_dp(W, capacity        , indx+1, N, dp_memo), &
                        rc_dp(W, capacity-W(indx), indx+1, N, dp_memo)+W(indx) )
     dp_memo(capacity, indx) = total_weight
  end if
end function rc_dp


program main
  implicit none
  interface
     recursive function rc_dp(W, capacity, indx, N, dp_memo) result(total_weight)
       implicit none
       integer,intent(in) ::W(:)
       integer::total_weight, capacity,indx, N
       integer,allocatable::dp_memo(:,:)
     end function rc_dp
  end interface
  integer::N,total,i,j,k, total_weight
  integer,allocatable::W(:)
  integer,allocatable::dp_memo(:,:)

  read *, N
  allocate(W(N))

  read *, W(1:N)
  total = SUM(W)

  if(MOD(total,2).eq.1) then
     print '(a)','impossible'
     return
  end if

  allocate(dp_memo(total/2,N+1))
  dp_memo(:,1:N)=-1
  dp_memo(:,N+1)=0

  total_weight = rc_dp(W, total/2, 1, N, dp_memo)

  if(total_weight.eq.total/2) then
     print '(a)','possible'
  else
     print '(a)','impossible'
  end if
end program main