#include <bits/stdc++.h>

using namespace std;

template<typename Weight, typename Value, typename Function> Value knapsack(Weight maxWeight, const vector<Weight>& weight, const vector<Value>& value, Value init = 0, Function func = plus<Weight>()) {
  vector<Value> dp(maxWeight + 1, 0);
  dp[0] = init;
  for (size_t i = 0; i < weight.size(); ++i) {
    for (auto w = maxWeight; w >= weight[i]; --w) {
      dp[w] = max(dp[w], func(dp[w - weight[i]], value[i]));
    }
  }
  return dp[maxWeight];
}

int main() {
  int n;
  cin >> n;
  vector<int> w(n);
  for (int& i : w) cin >> i;
  static const int sum = accumulate(w.begin(), w.end(), 0);
  cout << (sum % 2 == 0 && knapsack(sum / 2, w, vector<int>(n, 1), 1, multiplies<int>()) ? "possible" : "impossible") << endl;
}