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

#define REP(a, b) for(int a=0; a<(int)b; a++)

using namespace std;

int N;
vector <int> W;

bool roop(int max, int sum, int N, int pos){
  if(max < sum) return false;
  if(max == sum) return true;

  for(int i=pos; i<N; i++){
	if(roop(max, sum+W[i], N, i+1)) return true;
  }
  
  return false;;
}

int main(){
  cin >> N;
  W.resize(N);
  REP(i,N) cin >> W[i];

  int sum = 0;
  REP(i, N) sum += W[i];

  if(sum%2 == 0){
	if(roop(sum/2, 0, N, 0)) cout << "possible" << endl;
	else cout << "impossible" << endl;

  }else{
	cout << "impossible" << endl;
  }
  return 0;
}