#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vll = vector<long long>;

int main() {
    ll n;
    cin >> n;
    vll w(n);
    ll sum = 0;
    for (ll i = 0; i < n; i++) {
        cin >> w[i];
        sum += w[i];
    }
    if (sum % 2 != 0) {
        cout << "impossible" << endl;
    } else {
        vector<vector<ll>> dp(n + 1, vector<ll>(sum));
        dp[0][0] = 1;
        for (ll i = 0; i < n; i++) {
            for (ll j = 0; j < sum; j++) {
                if (dp[i][j] == 1) {
                    dp[i + 1][j] = 1;
                    if (j + w[i] < sum)
                        dp[i + 1][j + w[i]] = 1;
                }
            }
        }
        cout << ((dp[n - 1][(ll)sum / 2] == 1) ? "possible" : "impossible");
    }

    system("pause");
}