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

using namespace std;

int main()
{
    int n;
    cin >> n;
    vector<int> w(n);
    for (int i = 0; i < n; ++i)
    {
        cin >> w[i];
    }
    sort(w.begin(), w.end(), greater<int>());
    int left = 0, right = 0;
    for (auto wi : w)
    {
        if (left < right)
        {
            left += wi;
        }
        else
        {
            right += wi;
        }
    }
    cout << (left == right ? "possible" : "impossible") << endl;
    return 0;
}