#!/mnt/c/Users/moiki/bash/env/bin/python
# N,M = map(int, input().split())
N = int(input())
W = list(map(int, input().split()))

total_w = sum(W)
if total_w % 2 == 1:
    print("impossible")
    exit(0)

from collections import deque
from copy import copy
dq = deque([ (0, [])] ) 
while dq:
    idx, lst = dq.popleft()
    if sum(lst) == total_w//2:
            print("possible")
            exit(0)
    elif idx == N:
        continue
    n_lst = copy(lst)
    dq.append( (idx+1, n_lst) )
    dq.append( (idx+1, n_lst+[W[idx]]) )
print("impossible")