import sys; input = sys.stdin.buffer.readline
sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

#処理内容
def main():
	N = int(input())
	W = getlist()
	s = sum(W)
	if s % 2 == 1:
		print("impossible")
		return

	s = int(s // 2)
	DP = [0] * (10 ** 4 + 1)
	DP[0] = 1
	for i in range(N):
		for j in range(10 ** 4, -1, -1):
			if DP[j] == 1:
				DP[j + W[i]] = 1

	if DP[s] == 1:
		print("possible")
	else:
		print("impossible")


if __name__ == '__main__':
	main()