#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
using T = tuple<int, int, int>;
#define al(a) a.begin(), a.end()
#define ral(a) a.rbegin(), a.rend()
#define sz(a) (int)a.size()
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rrep(i, n) for (int i = 1; i <= (n); ++i)
#define drep(i, n) for (int i = (n)-1; i >= 0; --i)
#define db(a, b) cout << #a << ": " << a << " " << #b << ": " << b << endl;

int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  rep(i, n) cin >> a[i];
  int tot = 0;
  rep(i, n) tot += a[i];
  if (tot % 2) {
    cout << "impossible" << endl;
    return 0;
  }

  int m = tot / 2;
  vector<int> dp(m + 1, -1);
  dp[0] = 1;
  rep(i, n) {
    drep(j, m) {
      if (dp[j] == -1) continue;
      if (j + a[i] > m) continue;
      dp[j + a[i]] = dp[j];
    }
  }

  if (dp[m] == 1)
    cout << "possible" << endl;
  else
    cout << "impossible" << endl;
  return 0;
}