#include <bits/stdc++.h>

using namespace std;

#define INF 2000000000
#define MOD 1000000007
typedef long long ll;
typedef pair<int, int> P;


int main()
{
	int n;
	cin >> n;

	int a[n];
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	ll sum = accumulate(a, a+n, 0);
	if (sum%2!=0) {
		cout << "impossible" << "\n";
		return 0;
	}

	ll h = sum/2;

	for (int all = 0; all < (1<<n); all++) {
		ll subsum = 0;
		for (int i = 0; i < n; i++) {
			if (all & (1<<i)) {
				subsum += a[i];
			}
		}
		if (subsum==h) {
			cout << "possible" << "\n";
			return 0;
		}
	}
	cout << "impossible" << "\n";
	return 0;

}