// No.4 おもりと天秤
#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];
    if (s % 2) {
        cout << "impossible" << endl;
        return 0;
    }
    vector<vector<bool>> dp(N + 1, vector<bool>(s + 1, false));
    dp[0][0] = true;
    for (int i = 0; i < N; ++i) {
        for (int j = 0; j <= s; ++j) {
            dp[i + 1][j] = dp[i][j];
            if (j - W[i] >= 0) {
                dp[i + 1][j] = dp[i + 1][j] || dp[i][j - W[i]];
            }
        }
    }
    if (dp[N][s / 2]) cout << "possible" << endl;
    else cout << "impossible" << endl;
}