n=int(input())
W=list(map(int,input().split()))

if sum(W)%2!=0:
  print('impossible')
  exit()
dp=[[False]*(100*100) for _ in range(n)]
dp[0][0],dp[0][W[0]]=True,True
for i in range(n-1):
  for j in range(100*100):
    if dp[i][j]==True:
      dp[i+1][j+W[i]]=True
      dp[i+1][j]=True
for i in range(n):
  if dp[i][sum(W)//2]==True:
    print('possible')
    exit()
else:
  print('impossible')