N = int(input())
Ws = list(map(int, input().split()))


def solve(N, Ws):
    sumWs = sum(Ws)
    if sumWs & 1:
        return False
    half = sumWs // 2
    dp = set([0])
    for w in Ws:
        new_dp = set(dp)
        for v in dp:
            nv = v + w
            if nv == half:
                return True
            if nv < half:
                new_dp.add(nv)
        dp = new_dp
    return False

if solve(N, Ws):
    print('possible')
else:
    print('impossible')