#include <bits/stdc++.h>

#define REP(i, x, n) for(int i = x; i < (int)(n); i++)
#define rep(i, n) REP(i, 0, n)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define F first
#define S second
#define mp make_pair

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;

int main() {
  // ios_base::sync_with_stdio(false);
  int N;
  cin >> N;

  vector<int> w(N);
  int sum = 0;
  rep(i, N) {
    cin >> w[i];
    sum += w[i];
  }

  if(sum % 2) {
    cout << "impossible" << endl;
    return 0;
  }
   
  vector<bool> dp(sum + 1, false);
  dp[0] = true;
  
  rep(i, w.size()) for(int j = sum; j >= 0; j--) {
    if(dp[j]) dp[j + w[i]] = true;
  }

  cout << (dp[sum / 2] ? "possible" : "impossible") << endl;
  
  return 0;
}