#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(){
  int n;
  vector<int> vec;
  cin >> n;
  int tmp;
  for(int i=0;i<n;i++){
    cin >> tmp;
    vec.push_back(tmp);
  }
  
  sort(vec.begin(), vec.end());
  
  int left,right;
  left = right = 0;
  
  for(int i=0;i<vec.size();i++){
    if(left < right){
      left += vec[n-i-1];
    }else{
      right += vec[n-i-1];
    }
  }
  
  if(left == right){
    cout << "possible" << endl;
  }else{
    cout << "impossible" << endl;
  }
}