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

using ll = long long;
using P = pair<int, int>;

const int INF = 1e9;
const int MOD = 1e9 + 7;

bool flag[10010];

int main() {
  int W;
  cin >> W;
  int a[W];
  for (int i = 0; i < W; i++) cin >> a[i];

  int sum = accumulate(a, a + W, 0);
  if (sum & 1) {
    cout << "impossible" << endl;
  } else {
    flag[0] = true;
    for (int i = 0; i < W; i++) {
      for (int j = 10010; j >= a[i]; j--) {
        flag[j] |= flag[j-a[i]];
      }
    }
    cout << (flag[sum/2] ? "possible" : "impossible") << endl;
  }

  return 0;
}