def solve(n, w_list):
    total = sum(w_list)
    if total % 2 != 0:
        return "impossible"

    k = total // 2
    dp = [False] * (k + 1)
    dp[0] = True
    for w in w_list:
        for i in range(len(dp)):
            if dp[i] and i + w < len(dp):
                dp[i + w] = True

    return "possible" if dp[k] else "impossible"


def main():
    n = int(input())
    w_list = list(map(int, input().split()))
    print(solve(n, w_list))


if __name__ == '__main__':
    main()