N = int(input())
l = list(map(int, input().split()))
sum = 0
for i in l:
    sum += i

def part_sum0(a, A):
    # 初期化
    N = len(a)
    dp = [[0 for i in range(A + 1)] for j in range(N + 1)]
    dp[0][0] = 1

    # DP
    for i in range(N):
        for j in range(A + 1):
            if a[i] <= j:  # i+1番目の数字a[i]を足せるかも
                dp[i + 1][j] = dp[i][j - a[i]] or dp[i][j]
            else:  # 入る可能性はない
                dp[i + 1][j] = dp[i][j]
    return dp[N][A]

if isinstance(sum/2, int):
    test = part_sum0(l,int(sum/2))
    if test:
        print('possible')
    else:
        print('impossible')
else:
    print('impossible')