#include <iostream>
#include <cstdio>
#include <vector>
#include <list>
#include <map>
#include <queue>
#include <set>
#define rep(i, n) for(int (i)=0; (i)<(n); ++(i))
using namespace std;

int main()
{
    int n;
    cin >> n;
    int w[100];
    map<int, bool> m;
    m[0] = true;
    int sum = 0;
    rep(i, n) {
        cin >> w[i];
        sum += w[i];
    }

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

    rep(i, n) {
        map<int, bool> mm;
        for(map<int, bool>::iterator itr = m.begin(); itr != m.end(); ++itr) {
            if(i + itr->first ==  sum / 2) {
                cout << "possible" << endl;
                return 0;
            }
            mm[i + itr->first] = true;
        }

        for(map<int, bool>::iterator itr = mm.begin(); itr != mm.end(); ++itr) {
            m[itr->first] = true;
        }
    }

    cout << "impossible" << endl;
	return 0;
}