n = int(input())
A = [0] + list(map(int,input().split()))
w = sum(A)
dp = [[False for _ in range(w + 1)] for _ in range(n + 1)]
dp[0][0] = True
for i in range(1,n + 1):
	for j in range(1,w + 1):
		if j - A[i] >= 0:
			dp[i][j] = dp[i - 1][j - A[i]] or dp[i - 1][j]
		else:
			dp[i][j] = dp[i - 1][j]
if w % 2 == 1:
	print("impossible")
elif dp[n][w//2]:
	print("possible")
else:
	print("impossible")