#動的計画法、ビット全探索
def is_subset_sum(arr, target):
    n = len(arr)
    # DPテーブルの初期化
    dp = [[False] * (target + 1) for _ in range(n + 1)]
    # 初期条件
    for i in range(n + 1):
        dp[i][0] = True

    for i in range(1, n + 1):
        for j in range(1, target + 1):
            if arr[i - 1] > j:
                dp[i][j] = dp[i - 1][j]
            else:
                dp[i][j] = dp[i - 1][j] or dp[i - 1][j - arr[i - 1]]

    return dp[n][target]

N=int(input())
W=list(map(int,input().split()))
s=0
for i in range(N):
    s += W[i]

if s%2!=0:
    print("impossible")
elif is_subset_sum(W,s/2):
    print("possible")
else:
    print("impossible")