#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
  int n,w,s,a;
  cin>>n;
  vector<int> v;
  s=0;
  for(int i=0; i<n; ++i){
    cin>>w;
    s+=w;
    v.push_back(w);
  }
  if(s%2!=0){
    cout<<"impossible"<<endl;
    return 0;
  } else {
    a=s/2;
    int arr[a+1];
    for(int i=0; i<a+1; ++i){
      arr[i]=-1;
    }
    arr[0]=0;
    for(int i=0; i<n; ++i){
      for(int j=a; j>=0; --j){
        if(arr[j]!=-1){
          if(v[i]+j<=a && arr[v[i]+j]==-1){
            if(v[i]+j==a){
              cout<<"possible"<<endl;
              return 0;
            }
            arr[v[i]+j]=v[i];
          }
        }
      }
    }
  }
  cout<<"impossible"<<endl;
  return 0;
}