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

int main(){
    int N;
    cin >> N;
    vector<int> W(N);
    int sum = 0;
    for(int i = 0; i < N; i++){
        cin >> W.at(i);
        sum += W.at(i);
    }

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

    vector<vector<bool>> dp(N+1, vector<bool>(sum+1,false));
    dp.at(0).at(0) = true;
    for(int i = 0; i < N; i++){
        for(int j = 0; j <= sum; j++){
            if(j-W.at(i) >= 0) dp.at(i+1).at(j) = dp.at(i+1).at(j) || dp.at(i).at(j-W.at(i));
            dp.at(i+1).at(j) = dp.at(i+1).at(j) || dp.at(i).at(j);
        }
    }
    if(dp.at(N).at(sum/2)) cout << "possible" << endl;
    else cout << "impossible" << endl;
}