#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>
#include <complex>
#include <cassert>

using namespace std;

int main(){

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

    if (S % 2 == 1){
        cout << "impossible" << endl;
        return 0;
    }

    S /= 2;

    deque<bool> ok(S+1);
    ok[0] = 1;

    for (int i=0; i<N; i++){
        deque<bool> ko = ok;
        for (int j=0; j<=S; j++){
            if (j+W[i] <= S) ko[j+W[i]] |= ok[j];
        }
        swap(ko, ok);
    }

    cout << (ok[S] ? "possible" : "impossible") << endl;

    return 0;
}