N = int(input())
W = list(map(int,input().split()))
T = sum(W)
if T%2:
    print('impossible')
    exit()
T //= 2
if W[0] == T:
    print('possible')
    exit()
S = set([W[0]])
for i in range(1,N):
    temp = []
    for x in S:
        a = x + W[i] 
        if a == T:
            print('possible')
            exit()
        elif a < T:
            temp.append(a)
    S.update(temp)
print('impossible')