N = int(input())

W = list(map(int,input().split()))

dic = {}
dic[0] = 1

for i in range(N):

    loop = len(dic)
    q = []

    for j in dic:
        q.append(j+W[i])
    for j in q:
        dic[j] = 1

if sum(W) % 2 == 0 and sum(W) // 2 in dic:
    print ("possible")
else:
    print ("impossible")