n = int(input())
w = list(map(int,input().split()))
t = sum(w)
table = [[0 for i in range(n+1)] for k in range(n+1)]

if t % 2 == 1:
	print('impossible')
else:
	for i in range(1,n+1):
		table[0][i] = w[i-1]
		table[i][0] = w[i-1]
	for i in range(1,n+1):
		for k in range(1,n+1):
			if i == k:
				table[i][k] = table[i-1][k]
			else:
				if table[i-1][k]+table[i][0] <= t//2:
					table[i][k] = table[i-1][k]+table[i][0]
				else:
					table[i][k] = table[i-1][k]
	if t//2 in table[n]:
		print('possible')
	else:
		print('impossible')