n=int(input())
w=list(map(int,input().split()))
s=sum(w)
if s%2!=0:
  print('impossible')
  exit()
x=s//2
dp=[[0]*(x+1) for i in range(n+1)]
dp[0][0]=1
for i in range(n):
  for j in range(x+1):
    dp[i+1][j]=dp[i][j]|dp[i+1][j]
    if j+w[i]<=x:
      dp[i+1][j+w[i]]=dp[i][j]|dp[i+1][j+w[i]]
if dp[-1][-1]==1:
  print('possible')
else:
  print('impossible')