#include <iostream>
#include <vector>
#include <map>
using namespace std;
using vi = vector<int>;
#define rep(i,n) for(int i=0,_i=(n);i<_i;++i)

int N;
vi W;

map<int, bool> dp[100];
bool dfs(int i, int sum) {
  if (i == N)
    return sum == 0;
  if (dp[i].count(sum) != 0)
    return dp[i][sum];
  return dp[i][sum] = dfs(i+1, sum+W[i]) || dfs(i+1, sum-W[i]);
}
int main() {
  cin >> N;

  W.resize(N);
  int sum = 0;
  rep(i, N) {
    cin >> W[i];
    sum += W[i];
  }
  if (sum % 2 == 1) {
    cout << "impossible\n";
    return 0;
  }
  if (dfs(0, 0))
    cout << "possible\n";
  else
    cout << "impossible\n";

  return 0;
}