#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
  int n; cin >> n;
  vector<int> w(n);
  for(int i = 0; i < n; i++) cin >> w[i];
  sort(w.begin(), w.end());
  int sum = 0;
  for(int i = 0; i < n; i++) sum += w[i];
  bool ans = false;
  int sum2 = 0;
  for(int i = 0; i < n; i++){
    sum2 += w[i];
    if(sum2*2==sum) ans = true;
  }
  if(ans) cout << "possible" << endl;
  else cout << "impossible" << endl;
  return 0;
}