N = int(input())
W = list(map(int, input().split()))
dp = [False] * (1 << 15)
dp[0] = True
for i in range(N):
    for j in range(1 << 14, -1, -1):
        dp[j] |= dp[j - W[i]]
print('possible' if sum(W) & 1 == 0 and dp[sum(W) // 2] else 'impossible')