import sequtils
import strutils
import bitops
import math
import deques

proc get[T](s:seq[T],index :int):T=
    if index < 0 or s.len <= index:
        return false
    return s[index]

var n = stdin.readLine.parseInt
var a = stdin.readLine.split.map parseInt
var half = (a.sum div 2)
var DP = newSeqWith(n+1,newSeqWith(half+1,false))
DP[0][0] = true

for i in 1..n:
    for j in 0..half:
        DP[i][j] = DP[i-1][j] or DP[i-1].get(j-a[i-1])

if a.sum mod 2 == 1:
    echo "impossible"
else:
    echo if DP[n][half]:"possible"else:"impossible"