#include <bits/stdc++.h>
using namespace std;

int main() {
    int N;
    cin >> N;

    bitset<10010> bit(1);
    int SUM = 0;
    for (int i = 0; i < N; i++) {
        int w;
        cin >> w;
        SUM += w;
        bit |= (bit << w);
    }
    cout << (SUM % 2 == 0 && bit[SUM / 2] ? "possible" : "impossible") << endl;
}