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

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

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

    if(total % 2){
        cout << "impossible" << endl;
    }else{
        cout << "possible" << endl;
    }

    return 0;
}