def balance(weights: list) -> str:
    total_weight = sum(weights)
    if total_weight % 2 != 0:
        return "impossible"
    half_weight = total_weight // 2
    possible = [False] * (half_weight + 1)
    possible[0] = True
    for weight in weights:
        for i in range(half_weight, weight - 1, -1):
            if possible[i - weight]:
                possible[i] = True
    return "possible" if possible[half_weight] else "impossible"
N = int(input())
W = list(map(int, input().split()))
print(balance(W))