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

# dp[i][j]: i番目までのおもりで左-右がjになるかどうか
dp = [[False] * 10001 for _ in range(N + 1)]

dp[0][0] = True
for i in range(N):
    for j in reversed(range(10001)):
        w = W[i]
        if j + w < 10001:
            dp[i + 1][j] |= dp[i][j + w]
        if j - w >= 0:
            dp[i + 1][j] |= dp[i][j - w]

if dp[N][0]:
    print("possible")
else:
    print("impossible")