#include <bits/stdc++.h>
#include <iostream>
#include<math.h>
using namespace std;
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
vector<int>vec;
int avg;
int N;
bool dfs(int index, int now) {
    int n = vec[index];
    int add_case = now + n;
    if (now == avg) return true;
    if (index < N) {
        return (dfs(index+1, add_case) || dfs(index+1, now));
    } else {
        return false;
    }
}
int main()
{
    cin >> N;
    vec.resize(N);
    int sum = 0;
    for (int i=0; i<N; i++) {
        cin >> vec.at(i);
        sum += vec[i];
    }

    if (sum % 2 != 0) {
        cout << "impossible" << endl;
    } else {
        avg = sum/2;
        if (dfs(0, 0)) {
            cout << "possible" << endl;
        } else {
            cout << "impossible" << endl;
        }
    }
    return 0;
}