n = int(input())
w_list = list(map(int, input().split()))
dp = [False] * 10001
dp[0] = True

for w in w_list:
    for i in reversed(range(len(dp) - w)):
        if dp[i]:
            dp[i + w] = True

if sum(w_list) % 2 == 0 and dp[sum(w_list) // 2]:
    print('possible')
else:
    print('impossible')