n = int(input())
weights = list(map(int, input().split()))
total = sum(weights)

if total % 2 != 0:
    print("impossible")
else:
    target = total // 2
    dp = [False] * (target + 1)
    dp[0] = True
    for w in weights:
        for j in range(target, w - 1, -1):
            if dp[j - w]:
                dp[j] = True
    print("possible" if dp[target] else "impossible")