def solve():
    N, *W = map(int, open(0).read().split())
    q, r = divmod(sum(W), 2)
    if r == 1:
        return False

    dp = [False] * (q + 110)
    dp[0] = True

    for w in W:
        for i in reversed(range(q + 1)):
            if dp[i]:
                dp[i + w] = True
    return dp[q]

if solve():
    print("possible")
else:
    print("impossible")