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

weight_sum = sum(W)
if weight_sum % 2 == 1:
    print('impossible')
    exit()
half = sum(W) // 2

dp = [[False] * (half + 1) for _ in range(N)]
dp[0][0] = True

for i in range(N - 1):
    for j in range(half + 1):
        dp[i + 1][j] |= dp[i][j]
        if j - W[i] >= 0:
            dp[i + 1][j] |= dp[i][j - W[i]]
if dp[-1][half] >= 1:
    print('possible')
else:
    print('impossible')