#include <iostream>
#include <cstring>
#include <vector>
#include <numeric>

using namespace std;

int main()
{
  int N, tmp, sum;
  vector<int> x;

  cin >> N;
  for(int i=0; i<N; ++i){
    cin >> tmp;
    x.push_back(tmp);
  }
  sum = accumulate(x.begin(), x.end(), 0);

  if(sum%2){
    cout << "impossible" << endl;
    return 0;
  }

  bool dp[N+10][sum+10];
  memset(dp, 0, sizeof(dp));
  dp[0][0] = true;

  for(int i=0; i<N; i++){
    for(int j=0; j<=sum; j++){
      if(dp[i][j] || (j>=x[i] && dp[i][j-x[i]])){
        dp[i+1][j] = true;
      }
    }
  }
  for(int i=0; i<=N; i++){
    if(dp[i][sum/2]){
      cout << "possible" << endl;
      return 0;
    }
  }
  cout << "impossible" << endl;
  return 0;
}