#include <iostream>
#include <vector>

using namespace std;

int main(){
    int n;
    cin >> n;
    vector<int> v(n);
    int sum=0;
    for(int i=0; i<n; ++i){
        cin >> v[i];
        sum+=v[i];
    }
    if(sum%2==1){
        cout << "impossible\n";
        return 0;
    }
    int lim=sum/2;
    vector<bool> cache(lim+1, false);
    cache[0]=true;
    for(auto vi : v){
        for(int i=lim; i>=0; --i){
            if(i>=vi){
                cache[i]=cache[i] | cache[i-vi];
            }
        }
    }
    if(cache[lim]){
        cout << "possible\n";
    } else{
        cout << "impossible\n";
    }
    return 0;
}