#include <bits/stdc++.h>

using namespace std;

int main(void) {
  int n;
  cin >> n;

  int sum = 0;
  vector<int> w(n);
  for (int i = 0; i < n; i++) {
    cin >> w[i];
    sum += w[i];
  }

  if (sum & 1) {
    cout << "impossible\n";
  } else {
    sum >>= 1;
    bool dp[10010] = {};
    dp[0] = true;
    for (int i = 0; i < n; i++) {
      for (int j = sum; j >= 0; j--) {
        if (j < w[i]) continue;
        dp[j] |= dp[j - w[i]];
      }
    }
    cout << (dp[sum] ? "possible" : "impossible") << endl;
  }

  return 0;
}