#include <iostream>
#include <vector>
using namespace std;

int main() {
    int N;
    cin >> N;
    vector<int> W(N);
    int S = 0;
    for (int i = 0; i < N; ++i) {
        cin >> W[i];
        S = W[i];
    }

    vector<vector<bool>> dp(N + 1, vector<bool>(S + 1, false));
    dp[0][0] = true;
    for (int i = 1; i <= N; ++i) {
        for (int s = 0; s <= S; ++s) {
            if (s + W[i - 1] <= S) {
                dp[i][s] = dp[i - 1][s + W[i - 1]];
            }
            if (s - W[i - 1] >= 0) {
                dp[i][s] = dp[i - 1][s - W[i - 1]];
            }
        }
    }

    if (dp[N][0]) {
        cout << "possible" << endl;
    } else {
        cout << "impossible" << endl;
    }
}