#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
using namespace std;
using ll = long long;
using pii = pair<int, int>;

int main() {
  int n;
  cin >> n;
  vector<int> w(n);
  rep(i, n) cin >> w[i];
  int s = 0;
  rep(i, n) s += w[i];
  if (s & 1) {
    cout << "impossible" << endl;
    return 0;
  }
  vector<int> dp(10005);
  dp[0] = 1;
  rep(i, n) {
    vector<int> d = dp;
    for (int j = 0; j <= s; j++) {
      if (j + w[i] <= s) dp[j + w[i]] |= d[j];
    }
  }
  if (dp[s / 2]) cout << "possible" << endl;
  else cout << "impossible" << endl;
  return 0;
}