#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <sstream>   // istringstream
#include <algorithm> // sort
#include <utility>   // pair
#include <cfloat>    // DBL_MAX

typedef long long ll;
using namespace std;

bool rec(vector<int> vec, int idx, int N, int tgt){
  if(idx >= N || tgt < 0){ return false; }
  if(vec[idx] == tgt) { return true; }

  return rec(vec, idx+1, N, tgt-vec[idx])
    || rec(vec, idx+1, N, tgt);
}

int main(){
  int N; // [100]
  cin >> N;

  vector<int> weights (N); // [100]
  int sum=0;
  for(int i=0; i<N; i++){
    cin >> weights[i];
    sum += weights[i];
  }

  //// main
  if(sum%2 || !rec(weights, 0, N, sum/2)){
    cout << "impossible" << endl;
  } else {
    cout << "possible" << endl;
  }

  return 0;
}