n = int(input())
w = list(map(int,input().split()))
tt = sum(w)
t = int(tt//2)
table = [[0 for i in range(t+1)] for k in range(n+1)]
for i in range(t+1):
	if i == 0:
		table[0][0] = True
	else:
		table[0][i] = False
if tt%2 != 0:
	print('impossible')
else:
	for i in range(1,n+1):
		for k in range(t+1):
			if table[i-1][k]:
				table[i][k]=table[i-1][k]
			elif w[i-1]<=k:
				if table[i-1][k-w[i-1]]:
					table[i][k]=table[i-1][k-w[i-1]]
				else:
					table[i][k] = False
			else:
				table[i][k] = False
	if table[n][t]:
		print('possible')
	else:
		print('impossible')