N = int(raw_input())
W = map(int,raw_input().split())
wSum = sum(W)
dp = [0 for i in range(10100 + 1)]
dp[0] = 1
for i in range(N):
	for j in range(10000 + 1):
		if dp[j] == 1:
			dp[j + W[i]] = 1
if wSum % 2 == 0 and dp[wSum / 2] == 1:
	print 'possible'
else:
	print 'impossible'