n = int(input())
w_list = list(map(int, input().split()))

sum_w = sum(w_list)
result = 'impossible'

if sum_w % 2 == 0:
    harf_sum_w = sum_w // 2
    dp = [False] * (harf_sum_w + 1)
    dp[0] = True
    for w in w_list:
        if w > harf_sum_w:
            break
        for i in reversed(range(w, len(dp))):
            dp[i] |= dp[i - w]
    else:
        # print(dp)
        if dp[harf_sum_w]:
            result = 'possible'

print(result)