def search(N, ws, Sum):
    q = [Sum]
    s = [0]
    while q:
        target = q.pop(0)
        start = s.pop(0)
        for i in range(start, N):
            d = target - ws[i]
            if d == 0:
                res = True
            elif d < 0:
                if i == N-1:
                    res = False
                else:
                    continue
            elif d > 0:
                q_ = [target - ws[j] for j in range(i, N)]
                q.extend(q_)
                s_ = [j for j in range(i, N)]
                s.extend(s_)
                del q[0:N-i-1]
                break
    return res

def main():
    N = int(input())
    ws = list(map(int, input().split()))
    ws.sort()
    ws.reverse()
    ws_sum = sum(ws)
    if ws_sum % 2 == 0:
        Sum = ws_sum // 2
        res = search(N, ws, Sum)
    else:
        res = False
    if res:
        print('possible')
    else:
        print('impossible')

main()