#include <bits/stdc++.h>
using namespace std;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
#endif
using ll = long long;
using ld = long double;
const ll INF = 1ll<<60;
const ld EPS = 1.0/1e9;
#define endl "\n"
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define fore(i,a) for(auto &i:a)
#define all(x) (x).begin(),(x).end()
#define del(x) sort(all(x)); x.erase(unique(all(x)),x.end());

int main(){
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  ll n; cin >> n;
  vector<ll>a(n); ll sum=0;
  rep(i,0,n){
    cin >> a[i]; sum+=a[i];
  }
  if(sum%2==1){
    cout << "impossible" << endl;
    return 0;
  }
  vector<vector<bool>>dp(n+1,vector<bool>(sum+1));
  dp[0][0]=true;
  rep(i,0,n) rep(j,0,sum){
    if(dp[i][j]){
      dp[i+1][j]=true;
      if(a[i]+j>sum) continue;
      dp[i+1][a[i]+j]=true;
    }
  }
  if(dp[n][sum/2]) cout << "possible" << endl;
  else cout << "impossible" << endl;
}