class Yukicoder:
    def __init__(self):
        self.n = int(input())
        self.w_list = [int(i) for i in input().split()]

    def run(self):
        total = sum(self.w_list)
        if total & 1: return "impossible"

        half = total >> 1
        dp = [0]*10001
        dp[0] = 1
        for i in reversed(range(10001)):
            for w in self.w_list:
                if dp[i] == 1:
                    dp[i+w] = 1

        return "possible" if dp[half] == 1 else "impossible"

y = Yukicoder()
print(y.run())