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

w_sum = 0
for i in w:
    w_sum += i

if w_sum % 2 == 1:
    print("impossible")

elif w_sum % 2 == 0:
    dp = [False for _ in range(w_sum // 2 + 1)]
    dp[0] = True
    for i in range(n):
        dp_i = dp.copy()
        for j in range(w_sum // 2 + 1):
            if dp_i[j] and j + w[i] <= w_sum // 2:
                dp[j + w[i]] = True
    if dp[-1]:
        print("possible")
    else:
        print("impossible")