def read_int(): return int(input())
def read_int_list(): return list(map(int, input().split()))


N = read_int()
Ws = read_int_list()
S = sum(Ws)
if S & 1 != 0:
    print("impossible")
else:
    dp = [False] * 10001
    dp[0] = True
    for wi in Ws:
        for j in range(S // 2, -1, -1):
            if j + wi <= S and dp[j]:
                dp[j + wi] = True
    print("possible" if dp[S // 2] else "impossible")