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

int N;
vector<int> arr;
vector<unordered_map<int, bool>> memo;
bool ans;

bool solve(int n, int left)
{
	if (n == arr.size())
		return !left;
	else if (left < 0)
		return false;
	else
	{
		if (memo[n].find(left) != memo[n].end())
			return memo[n][left];
		else
		{
			if (solve(n + 1, left))
			{
				memo[n][left] = true;
				return true;
			}
			else
				memo[n][left] = false;
		}

		if (memo[n].find(left - arr[n]) != memo[n].end())
			return memo[n][left - arr[n]];
		else
		{
			if (solve(n + 1, left - arr[n]))
			{
				memo[n][left - arr[n]] = true;
				return true;
			}
			else
				memo[n][left - arr[n]] = false;
		}

		return false;
	}
}

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

	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;
}