#include <bits/stdc++.h>
using namespace std;

int main(){
  int n; cin >> n;
  vector<int> w(n);
  int sum=0;
  for(int i=0; n>i; ++i){
    cin >> w[i]; sum+=w[i];
  }
  bool dp[sum+1][n+1];
  for(int i=0; sum>=i; ++i) for(int j=0; n>=j; ++j) dp[i][j] = false;
  dp[0][0]=true;
  for(int i=1; n>=i; ++i){
    for(int j=1; sum>=j; ++j){
      dp[i][j] = dp[i-1][j-w[i-1]];
    }
  }
  if(sum%2 == 0){
    if(dp[sum/2][n]){
      cout << "possible" << endl;
      return 0;
    }
  }
  cout << "impossible" << endl;
}