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 w in self.w_list: for i in reversed(range(10001)): if dp[i] == 1: dp[i+w] = 1 return "possible" if dp[half] == 1 else "impossible" y = Yukicoder() print(y.run())