#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<int, int> PII;

#define FOR(i, a, n) for (int i = (int)a; i < (int)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define MOD 1000000007
#define INF 1000000000
#define PI 3.14159265359
#define EPS 1e-12

int main(void)
{
  int n;
  cin >> n;
  int w[100], sum = 0;
  REP(i, n) {
    cin >> w[i];
    sum += w[i];
  }

  if(sum % 2) {cout << "impossible" << endl; return 0;}
  bool p[10000] = {false};
  p[0] = true;
  REP(i, n) {
    for(int j=sum/2; j>=0; j--) {
      if(p[j]) p[j+w[i]] = true;
    }
  }
  if(p[sum/2]) cout << "possible" << endl;
  else cout << "impossible" << endl;

  return 0;
}