#include <iostream>
#include <vector>

using namespace std;

int main()
{
  int N, tmp;
  vector<int> x;

  cin >> N;
  x.push_back(0);

  for(int i=1; i<=N; ++i){
    cin >> tmp;
    x.push_back(x[i-1]+tmp);
  }

  if(x.back()%2 == 1){
    cout << "impossible" << endl;
    return 0;
  }
  for(int i=1; i<N; ++i){
    for(int j=1; j<N-i+1; ++j){
      tmp = x[j+i-1] - x[j-1];
      if(tmp == x.back()/2){
        cout << "possible" << endl;
        return 0;
      }
    }
  }
  cout << "impossible" << endl;
  return 0;
}