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

S = sum(W)
if S % 2 != 0 or S//2 < max(W):
    print("impossible")
    exit()

dp1 = [0 for _ in range(S//2+1)]
dp1[W[0]] = 1

for k in range(1,N):
    dp2 = dp1[:]
    for l in range(S//2-W[k]+1):
        if dp1[l] == 1:
            dp2[l+W[k]] = 1
    dp2[W[k]] = 1
    dp1 = dp2[:]

print("possible" if dp1[S//2] == 1 else "impossible")