#include <iostream>
#include <vector>
using namespace std;

int main()
{
	int N; vector<int> W;

	cin >> N;
	W.push_back(0);
	for (int i = 0; i < N; ++i)
	{
		int tmp;
		cin >> tmp;
		W.push_back(tmp);
	}

	int sum = 0, hSum; vector<vector<bool>> memo;
	for (auto p : W)
		sum += p;
	
	if (sum % 2 != 0)
		cout << "impossible" << endl;
	else
	{
		hSum = sum / 2;
		memo.resize(N + 1);
		for (auto &p : memo)
			p.assign(hSum + 1, false);
		for (int i = 0; i <= N; ++i)
			memo[i][0] = true;

		for (int i = 1; i <= N; ++i)
		{
			memo[i] = memo[i - 1];
			for (int j = 0; j <= hSum; ++j)
			{
				if (j + W[i] <= hSum)
					memo[i][j + W[i]] = memo[i - 1][j] || memo[i][j + W[i]];
			}
		}

		cout << (memo[N][hSum] ? "possible" : "impossible") << endl;
	}

	return 0;
}