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

sum = sum(W)
if sum % 2 != 0:
    print("impossible")
    exit()

dp = [[0] * 10001 for i in range(N + 1)]
dp[0][0] = 1
idx = 0

for w in W:
    for i in range(10000):
        if dp[idx][i] == 1:
            dp[idx + 1][i + w] = 1
            dp[idx + 1][i] = 1
    idx += 1

if dp[N][int(sum / 2)] == 1:
    print("possible")
else:
    print("impossible")