def solve():
    N = int(input())
    W = [int(i) for i in input().split()]
    Wt = sum(W)

    if Wt & 1:
        print('impossible')
        return

    Wh = Wt // 2

    dp = [False] * (Wh + 1)
    dp[0] = True

    for w in W:
        for i in range(Wh, w - 1, -1):
            dp[i] = dp[i] | dp[i - w]

    print('possible' if dp[Wh] else 'impossible')

if __name__ == '__main__':
    solve()