#include <iostream>
#include <queue>
#include <vector>
#include <cmath>
#include <algorithm>
#include <map>
#include <numeric>

using namespace std;
using ll = long long;
const ll INF = 1e9;
const ll MOD = 1e9 + 7;

int W[110];
bool dp[110][5010];

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

    if (sum % 2 > 0) {
        cout << "impossible" << endl;
        return 0;
    }
    int w = sum / 2;
    for (int i = 0; i < N; i++) {
        dp[i+1][W[i]] = true;
        for (int v = 0; v < w; v++) {
            dp[i+1][v] = true;
        }
    }

    cout << (dp[N][w] ? "possible" : "impossible") << endl;

    return 0;
}