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

int N; vector<int> arr; bool ans;

bool solve(int n, int left)
{
	if (n == arr.size())
		return !left;
	else
	{
		if (solve(n + 1, left) || solve(n + 1, left - arr[n]))
			return true;
		return false;
	}
}

int main()
{
	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))
		ans = solve(0, sum / 2);

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

	return 0;
}