#include <iostream>
#include <vector>
#include <array>
#include <string>

using namespace std;
const int MAX_N = 100;

int N;
vector<int> w_list;
int total = 0;
vector<bool> result(MAX_N * 100 + 1, false);

#define REP(i,first,last) for (int i=first;i<last;i++)

void solve(){
  result[0] = true;
  for (auto w: w_list) {
    for(int i=10000-w;i>=0;i--) {
      if (result[i]) {
        result[i+w] = true;
      }
    }
  }
}

int main(){
  cin >> N;
  
  REP(i,0,N) {
    int val;
    cin>>val;
    w_list.push_back(val);
    total += val;
  }
  if (total & 1) {
    cout<<"impossible"<<endl;
  } else {
    solve();
    if (result[total>>1]) {
      cout<<"possible"<<endl;
    } else {
      cout<<"impossible"<<endl;
    }
  }
}