import queue


def main():
    n = int(input())

    w = list(map(int, input().split()))

    w_sum = sum(w)

    if w_sum % 2 == 1:
        print("impossible")
        return

    dp = [[False for _ in range(w_sum + 1)] for _ in range(n + 1)]

    dp[0][0] = True

    for i in range(n):
        for j in range(w_sum + 1):
            dp[i + 1][j] |= dp[i][j]
            if j + w[i] <= w_sum:
                dp[i + 1][j + w[i]] |= dp[i][j]

    print("possible" if dp[n][w_sum // 2] else "impossible")

    return


if __name__ == '__main__':
    main()