n = int(input())
w = list(map(int, input().split()))

weightSum = sum(w)

if weightSum % 2 == 1:
	print("impossible")

else:
	weightPossible = [0]*10001
	weightPossible[0] = 1

	for i in range(n):
		for j in reversed(range(10001)):
			if weightPossible[j - w[i]] == 1:
				weightPossible[j] = 1

	if weightPossible[weightSum // 2] == 1:
		print("possible")
	else:
		print("impossible")