N = int(input())
Ws = [int(i) for i in input().split()]

def solve(N, Ws):
    sumWs = sum(Ws)
    if sumWs % 2 != 0:
        return 'impossible'
    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 'possible'
            if nv < half:
                new_dp.add(nv)
        dp = new_dp
    return 'impossible'

print(solve(N, Ws))