#include <iostream>
#include <vector>

int main() {
    using namespace std;
    int n, tot = 0;
    cin >> n;
    vector<int> w(n);
    for (auto &e : w) {
        cin >> e;
        tot += e;
    }

    if (tot % 2 > 0) {
        cout << "impossible\n";
        return 0;
    }

    const int m = tot / 2;
    vector dp(n + 1, vector<bool>(m + 1, false));
    dp[0][0] = true;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j <= m; j++) {
            if (!dp[i][j]) { continue; }
            dp[i + 1][j] = true;
            if (j + w[i] <= m) { dp[i + 1][j + w[i]] = true; }
        }
    }
    cout << (dp[n][m] ? "possible\n" : "impossible\n");
}