#include <bits/stdc++.h>

using namespace std;

int main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  int N;
  cin >> N;
  vector<int> W(N);
  for (auto &w : W) {
    cin >> w;
  }
  int tot = std::accumulate(std::cbegin(W), std::cend(W), decltype(W)::value_type());
  vector dp(tot + 1, false);
  dp[0] = true;
  for (int i = 0; i < N; i++) {
    for (int w = tot; w > -1; w--) {
      if (w - W[i] >= 0) dp[w] = dp[w] | dp[w - W[i]];
    }
  }
  if (tot % 2 == 0 && dp[tot / 2]) {
    cout << "possible" << '\n';
  } else {
    cout << "impossible" << '\n';
  }
  return 0;
}