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

using namespace std;

#define REP(i,first,last) for (int i=first;i<last;i++)
#define FOR(it,con) for (auto it=con.begin();it!=con.end();it++)

int N;
int half;
vector<int> w_list;
bool dp[10001] = {false};

int main(){
  cin >> N;
  dp[0] = true;
  int val;
  int total = 0;
  REP(i,0,N){
    cin >> val;
    w_list.push_back(val);
    total += val;
  }
  if (total & 1) {
    cout<<"impossible"<<endl;
  } else {
    half = total >> 1;
    for (auto w: w_list) {
      for (int i=10000;i>=0;i--) {
        if (dp[i] == true) dp[i + w] = true;
      }
    }
    if (dp[half]) {
      cout<<"possible"<<endl;
    } else {
      cout<<"impossible"<<endl;
    }
  }
}