#include<iostream>
using namespace std;

int n;
int w;
int check[10001]={1};

int main(){
  int sum=0;

  cin >> n;

  for(int i=0;i<n;i++){
    cin >> w;
    sum+=w;
    for(int j=10000-w;j>=0;j--){
      check[j+w]+=check[j];
    }
  }

  if((sum%2==0)&&check[sum/2]) cout << "possible" << endl;
  else cout << "impossible" << endl;

}