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

int main()
{
	int N; vector<int> arr; bool ans = false;
	
	cin >> N;
	for (int i = 0; i < N; ++i)
	{
		int j;
		cin >> j;
		arr.push_back(j);
	}

	int sum = 0, nsum = 0;
	for (int i = 0; i < arr.size(); ++i)
		sum += arr[i];
	if (!(sum % 2))
	{
		sort(arr.begin(), arr.end());
		for (int i = 0; i < arr.size(); ++i)
		{
			nsum += arr[i];
			if (sum / 2 == nsum)
				ans = true;
			else if (sum / 2 < nsum)
				break;
		}
	}

	cout << (ans ? "possible" : "impossible") << endl;

	return 0;
}