N = int(input())
W = [0] + list(map(int,input().split()))
H = sum(W)//2
dp = [0] * (N+1) * 100
dp[0] = 1
for l in range(1,N+1):
  for i in reversed(range(0, (N+1) * 100)):
    if dp[i]:
      dp[i+W[l]] = 1
if sum(W) % 2 == 0 and dp[H] == 1:
  print('possible')
else:
  print('impossible')