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

int main()
{
    int n;
    cin >> n;
    vector<int> w(n);
    for (int i = 0; i < n; i++) cin >> w.at(i);
    int wsum = accumulate(w.begin(), w.end(), 0), whalf = wsum / 2;
    if (wsum % 2 != 0) {
        cout << "impossible" << endl;
        return 0;
    }
    vector<vector<bool>> s(n + 1, vector<bool>(whalf + 1, false));
    s.at(0).at(0) = true;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j <= whalf; j++) {
            if (s.at(i).at(j) || (j - w.at(i) >= 0 && s.at(i).at(j - w.at(i)))) s.at(i+1).at(j) = true;
        }
    }
    if (s.at(n).at(whalf)) {
        cout << "possible" << endl;
    } else {
        cout << "impossible" << endl;
    }
}