#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
#define REP(i, a, n) for(int i=0; i<n; i++)
#define RREP(i, n) for(int i=n-1; i>=0; i--)

int main()
{
	int N, sum=0;
	bool dp[10001] = {};
	vector<int> W;
	cin >> N;
	REP(i, 0, N) {
		int w;
		cin >> w;
		W.push_back(w);
		sum += w;
	}

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

	dp[0] = true;
	REP(i, 0, N) {
		RREP(j, sum) {
			if (dp[j]) dp[j + W[i]] = true;
		}
	}
	if (dp[sum / 2]) cout << "possible" << endl;
	else cout << "impossible" << endl;
    return 0;
}