N = int(input())
A = list(map(int, input().split()))

M = sum(A)
if M%2==1:
  print("impossible")
  exit()

L = M//2
dp = [0]*(L+1)
dp[0] = 1
for a in A:
  for i in range(L+1)[::-1]:
    if i-a >= 0:
      dp[i] |= dp[i-a]
print("possible" if dp[L] else "impossible")