def solve():
    def rec(m, weight, dp):
        if dp[m][weight] is None:
            dp[m][weight] = rec(m - 1, weight, dp)
            if weight - W[m - 1] >= 0:
                dp[m][weight] |= rec(m - 1, weight - W[m - 1], dp)

        return dp[m][weight]

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

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

    Wh = Wt // 2

    dp = [[None]*(Wh + 1) for i in range(N + 1)]

    dp[0][0] = True
    for i in range(1, Wh + 1):
        dp[0][i] = False
    judge = rec(N, Wh, dp)

    print('possible' if judge else 'impossible')

if __name__ == '__main__':
    solve()