N = int(input())
W = list(map(int, input().split()))
sum_W = sum(W)
ans = "impossible"
if sum_W % 2 == 1:
    pass
else:
    M = sum_W//2
    dp = [[False]*(M+1) for _ in range(N+1)]
    dp[0][0] = True
    for i in range(N):
        w = W[i]
        for j in range(M+1):
            if w < j:
                dp[i+1][j] = dp[i][j]
            else:
                dp[i+1][j] = dp[i][j-w] or dp[i][j]
    if dp[-1][-1]:
        ans = "possible"
print(ans)