#include <algorithm>
#include <iostream>
#include <vector>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;

#define MOD 1000000007
#define REP(i, N) for (int i = 0; i < N; ++i)
#define REP1(i, N) for (int i = 1; i <= N; ++i)
#define RREP(i, N) for (int i = N - 1; i >= 0; --i)
#define ALL(a) a.begin(), a.end()

bool dp[101][10001];

int main() {
  int n;
  cin >> n;
  int w[n];
  int sum = 0;
  REP(i, n) {
    cin >> w[i];
    sum += w[i];
  }
  if (sum % 2) {
    cout << "impossible" << endl;
    return 0;
  }
  dp[0][0] = true;
  REP(i, n) {
    for (int j = 0; j <= 10000; ++j) {
      dp[i + 1][j] |= dp[i][j];
      if (w[i] <= j) {
        dp[i + 1][j] |= dp[i][j - w[i]];
      }
    }
  }
  cout << (dp[n][sum / 2] ? "possible" : "impossible") << endl;
  return 0;
}