def solve():
    N = input()
    W = map(int, raw_input().split())

    S = sum(W)

    if S & 1:
        return False

    can = [False] * (S + 1)
    can[0] = True

    for w in W:
        for i in xrange(S - w, -1, -1):
            can[i + w] = can[i + w] or can[i]

    return can[S / 2]

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