import sequtils,strutils,math

var
  n = parseInt readLine stdin
  ws = stdin.readLine.split.map parseInt
  x = sum ws
  dp = false.repeat 10003
  result = "impossible"
dp[0] = true
if x mod 2 == 0:
  for i in 0..n - 1:
    for j in countdown(10000,0):
      if dp[j]: dp[j + ws[i]] = true
  if dp[x div 2]: result = "possible"
echo result