import sys,copy
input=lambda:sys.stdin.readline().rstrip()
N=int(input())
A=list(map(int,input().split()))
if sum(A)%2:
	print("impossible")
	sys.exit()
targ=sum(A)//2
dp=[[0 for j in range(targ+1)] for i in range(N+1)]
dp[0][0]=1
for i in range(N):
	dp[i+1]=copy.copy(dp[i])
	for j in range(targ+1-A[i]):
		dp[i+1][j+A[i]]|=dp[i][j]
print(["impossible","possible"][dp[N][targ]])