# -*- coding: utf-8 -*-

def main():

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

	target = sum(W) / 2
	queue = []
	queue.append(0)

	ans = "impossible"
	for i in W:
		for j in range(len(queue)):
			v = queue[j]
			queue.pop(j)
			num = i + v
			if num == target:
				ans = "possible"
				break
			elif num > target:
				queue.append(v)
			else:
				queue.append(num)
				queue.append(v)

	print(ans)

if __name__ == '__main__':
	main()