// unsolved
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll INF = 1LL << 60;

int main() {
  int n;
  cin >> n;
  vector<int> w(n + 1);
  for (int i = 1; i <= n; i++) cin >> w[i];
  int sum = 0;
  for (int i = 1; i <= n; i++) sum += w[i];
  if (sum % 2) {
    cout << "impossible" << endl;
    return 0;
  }
  vector<bool> dp(1e4 + 10, false);
  dp[0] = true;
  for (int i = 1; i <= n; i++) {
    for (int j = sum; j >= w[i]; j--) {
      if (dp[j - w[i]]) dp[j] = true;
    }
  }
  if (dp[sum / 2]) {
    cout << "possible" << endl;
    return 0;
  }
  cout << "impossible" << endl;
}