#include <bits/stdc++.h> 

#define int long long

#define REP(i, b) for(int i = 0; i < (b); i++)
#define REPS(i, b) for(int i = 1; i <= (b); i++)
#define ALL(v) (v).begin(), (v).end()

using namespace std;

using pi = pair<int, int>;
using vi = vector<int>;
using vs = vector<string>;
using vb = vector<bool>;
using vpi = vector<pi>;
using vvi = vector<vi>;
using vvb = vector<vb>;

const int INF = 1e10;
const int MOD = 1e9+7;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

signed main()
{
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(10);

    int N; cin >> N;
    vi W(N); REP(i, N) cin >> W[i];
    REP(b, 1 << (N+1))
    {
        int x = 0, y = 0;
        REP(i, N)
        {
            if(b & (1 << i)) x += W[i];
            else y += W[i];
        }
        if(x == y)
        {
            cout << "possible" << endl;
            return 0;
        }
    }
    cout << "impossible" << endl;
}